Chain-extending amine end-capped polyimides

ABSTRACT

Aromatic polyimides with amine end groups are chain-extended (molecular weight increased) by reacting them with aromatic di- or tri- anhydrides. The reaction can either be at a temperature above the melting point of the reactants or in solvents for the reactants. The polyimides can be shaped and formed prior to chain-extending.

RELATIONSHIP TO OTHER APPLICATIONS

This application is a divisional of copending application Ser. No.363,801, filed May 25, 1973 now U.S. Pat. No. 3,897,395.

BACKGROUND OF THE INVENTION

1. Field of Invention

This invention relates to processes for preparing polymeric materialsand polymeric materials so prepared and more particularly to processesfor converting low molecular weight polyimides, with minimum eliminationof by-products, to high molecular weight, thermally-stable polymers.

2. Prior Art

The synthesis in recent years of a number of thermally-stable polymers(e.g. polyimides) has supplied materials whose properties allow them tomeet some critical end-use requirements. Their application to other usesis limited by a number of their specific properties, among which isintractability. This necessitates their use in dilute solutions in suchexotic solvents as sulfuric acid, for example, to be spun into fibers.This excludes their use in laminations and in moldings. In addition,once isolated from the solvent, high temperatures are required toconvert them to the fully condensed or cured final state. This curing isaccompanied by the elimination of volatile by-products.

In contrast, polymers containing oxirane structures, such asepoxy-phenolics, can be cured at reasonably low temperatures with aminimum of by-products. However, the thermal stabilities of the oxiranepolymers fall below those, for example, of the stablepolybenzimidazoles. Thus, it is desirable to prepare oligomers whichwill propagate to higher molecular weights with minimum volatileelimination at relatively low temperatures and which will possessthermal stabilities reasonably higher than epoxy phenolics, preferablyapproaching the stabilities demonstrated by the polyimides and similarpolyheterocyclics.

SUMMARY OF THE INVENTION

According to the present invention there is provided a polymericchain-extending process comprising: reacting a polyimide of the formula:##STR1## WHEREIN Ar' is a tetravalent aromatic organic radical, the fourcarbonyl groups being attached directly to separate carbon atoms andeach pair of carbonyl groups being attached to adjacent carbon atoms inthe Ar' radical,

Ar is a divalent aromatic organic radical, and

n is a positive integer of at least 1 and preferably 3 or more, with ananhydride of the formula: ##STR2## wherein p is 2 or 3 and Ar' is asdefined above when p is 2, when p is 3 Ar' is a hexavalent aromaticorganic radical, the six carbonyl groups being attached directly toseparate carbon atoms and each pair of carbonyl groups being attached toadjacent carbon atoms in the Ar' radical.

There is also provided a cross-linked polymer prepared by theabove-described process.

DETAILED DESCRIPTION OF THE INVENTION

The polyimides used in the process of the present invention are preparedby reacting an aromatic dianhydride, an aromatic diamine and,optionally, an organic monoamine to form oligomeric or higher molecularweight polyimides. The aromatic dianhydride has the general formula:##STR3## wherein Ar' is a tetravalent aromatic organic radical,preferably containing at least one ring of six carbon atoms, said ringcharacterized by benzenoid unsaturation, the four carbonyl groups beingattached directly to separate carbon atoms and each pair of carbonylgroups being attached to adjacent carbon atoms in the Ar' radical. Anyof the aromatic tetracarboxylic acid dianhydrides known in the prior artcan be used. Among the useful dianhydrides are3,3',4,4'-benzophenonetetracarboxylic acid dianhydride, pyromelliticdianhydride, 2,3,6,7-naphthalene tetracarboxylic acid dianhydride,3,3',4,4'-diphenyl tetracarboxylic acid dianhydride, 1,2,5,6-naphthalenetetracarboxylic acid dianhydride, 2,2',3,3'-diphenyl tetracarboxylicacid dianhydride, 2,2-bis(3,4-dicarboxyphenyl)propane dianhydride,3,4,9,10-perylene tetracarboxylic acid dianhydride,bis(3,4-dicarboxyphenyl)ether dianhydride,naphthalene-1,2,4,5-tetracarboxylic acid dianhydride,naphthalene-1,4,5,8-tetracarboxylic acid dianhydride,decahydronaphthalene-1,4,5,8-tetracarboxylic acid dianhydride,4,8-dimethyl-1,2,3,5,6,7-hexahydronaphthalene-1,2,5,6-tetracarboxylicacid dianhydride, 2,6-dichloronaphthalene-1,4,5,8-tetracarboxylic aciddianhydride, 2,7-dichloronaphthalene-1,4,5,8-tetracarboxylic aciddianhydride, 2,3,6,7-tetrachloronaphthalene-1,4,5,8-tetracarboxylic aciddianhydride, phenanthrene-1,8,9,10-tetracarboxylic acid dianhydride,cyclopentane-1,2,3,4-tetracarboxylic acid dianhydride,pyrrolidine-2,3,4,5-tetracarboxylic acid dianhydride,pyrazine-2,3,5,6-tetracarboxylic acid dianhydride,2,2-bis(2,3-dicarboxyphenyl)propane dianhydride,1,1-bis(2,3-dicarboxyphenyl)ethane dianhydride,1,1-bis-(3,4-dicarboxyphenyl)ethane dianhydride,bis(2,3-dicarboxyphenyl)methane dianhydride,bis(3,4-dicarboxyphenyl)methane dianhydride,bis(3,4-dicarboxyphenyl)sulfone dianhydride, andbenzene-1,2,3,4-tetracarboxylic acid dianhydride. The first threementioned dianhydrides are preferred.

Aromatic diamines useful in preparing the starting polyimides and in theprocess have the general formula:

    NH.sub.2 -- Ar -- NH.sub.2

wherein Ar is a divalent aromatic organic radical. Preferred aromaticdiamines are those wherein Ar is a divalent benzenoid radical selectedfrom the group consisting of ##STR4## and multiples thereof connected toeach other by R^(IV), e.g., ##STR5## wherein R^(IV) is an alkylene chainof 1-3 carbon atoms, --CH═CH--, ##STR6## wherein R^(V) and R^(VI) areeach selected from the group consisting of alkyl and aryl containing oneto six carbon atoms, e.g., methyl, ethyl, hexyl, n-butyl, i-butyl andphenyl.

Examples of aromatic diamines which are suitable for use in the presentinvention are 4,4'-diaminodiphenyl propane, 4,4'-diamino-diphenylmethane, benzidine, 3,3'-dichlorobenzidine, 4,4'-diamino-diphenylsulfide, 3,3'-diamino-diphenyl sulfone, 4,4'-diamino-diphenyl sulfone,4,4'-diamino-diphenyl ether, 1,5-diamino naphthalene,4,4'-diamino-diphenyl diethylsilane, 4,4'-diamino-diphenyldiphenylsilane, 4,4'-diamino-diphenyl ethyl phosphine oxide,4,4'-diamino-diphenyl phenyl phosphine oxide, 4,4'-diamino-diphenylN-methyl amine, 4,4'-diamino-diphenyl N-phenyl amine and mixturesthereof. 3,3'-dimethyl-4,4'-diaminodiphenylmethane,3,3'-diethyl-4,4'-diaminodiphenylmethane,3,3'-dimethoxy-4,4'-diaminodiphenylmethane,3,3'-diethoxy-4,4'-diaminodiphenylmethane,3,3'-dichloro-4,4',4,4'-diaminodiphenylmethane,3,3'-dibromo-4,4'-diaminodiphenylmethane,3,3'-dicarboxy-4,4'-diaminophenylmethane,3,3'-dihydroxy-4,4'-diaminophenylmethane,3,3'-disulpho-4,4'-diaminodiphenylmethane,3,3'-dimethyl-4,4'-diaminodiphenylether,3,3'-diethyl-4,4'-diaminodiphenylether,3,3'-dimethoxy-4,4'-diaminodiphenylether,3,3'-diethoxy-4,4'-diaminodiphenylether,3,3'-dichloro-4,4'-diaminodiphenylether, 3,3'-dibromo-4,4'-diaminodiphenylether, 3,3'-dicarboxy-4,4'-diaminodiphenylether,3,3'-dihydroxy-4,4'-diaminodiphenylether,3,3'-disulfo-4,4'-diaminodiphenylether,3,3'-dimethyl-4,4'-diaminodiphenylsulfide,3,3'-diethyl-4,4'-diaminodiphenylsulfide,3,3'-dimethoxy-4,4'-diaminodiphenylsulfide,3,3'-diethoxy-4,4'-diaminodiphenylsulfide,3,3'-dichloro-4,4'-diaminodiphenylsulfide,3,3'-dibromo-4,4'-diaminodiphenylsulfide,3,3'-dicarboxyl-4,4'-diaminodiphenylsulfide,3,3'-dihydroxy-4,4'-diaminodiphenylsulfide,3,3'-disulfo-4,4'-diaminodiphenylsulfide,3,3'-dimethyl-4,4'-diaminodiphenylsulfone,3,3'-diethoxy-4,4'-diaminodiphenylsulfone,3,3'-dichloro-4,4'-diaminodiphenylsulfone,3,3'-dicarboxy-4,4'-diaminodiphenylsulfone,3,3'-dihydroxy-4,4'-diaminodiphenylsulfone,3,3'-disulfo-4,4'-diaminodiphenylsulfone,3,3'-diethyl-4,4'-diaminodiphenylpropane,3,3'-dimethoxy-4,4'-diaminodiphenylpropane,3,3'-dibromo-4,4'-diaminodiphenylpropane, 3,3'-dichloro-4,4'-diaminodiphenylpropane,3,3'-dicarboxy-4,4'-diaminodiphenylpropane,3,3'-dihydroxy-4,4'-diaminodiphenylpropane,3,3'-disulfo-4,4'-diaminodiphenylpropane,3,3'-dimethyl-4,4'-diaminobenzophenone,3,3'-dimethoxy-4,4'-diaminobenzophenone,3,3'-dichloro-4,4'-diaminobenzophenone,3,3'-dibromo-4,4'-diaminobenzophenone,3,3'-dicarboxy-4,4'-diaminobenzophenone,3,3'-dihydroxy-4,4'-diaminobenzophenone,3,3'-disulphodiaminobenzophenone, 3,3'-diaminodiphenylmethane,3,3'-diaminodiphenylether, 3,3'-diaminodiphenylsulfide,3,3'-diaminodiphenylsulfone, 3,3'-diaminodiphenylpropane,3,3'-diaminobenzophenone, 2,4-diaminotoluene, 2,6-diaminotoluene,1-isopropyl-2,4-phenylenediamine, 2,4-diaminoanisole,2,4-diaminomonochlorobenzene, 2,4-diaminofluorobenzene,2,4-diaminobenzoic acid, 2,4-diaminophenol, and2,4-diaminobenzenesulfonic acid, and phenylene diamines. Preferreddiamines are 4,4'-oxydianiline, 4,4'-sulfonyldianiline, 4,4'-methylenedianiline, 4,4'-diaminobenzophenone, 4,4'-diaminostilbene and thephenylene diamines.

The polyimide starting materials used in the process of the presentinvention are prepared according to the azeotroping process described inmy copending application Ser. No. 363,800, filed May 25, 1973 now U.S.Pat. No. 3,998,786, the disclosure of which is hereby incorporated byreference. Briefly, the process involves reacting the dianhydride withthe diamine in a phenol solvent of the formula ##STR7## where each R' ishydrogen or a methyl radical in the presence of certain organicazeotroping agents, particularly cyclic hydrocarbons of 6 to 8 carbonatoms and most preferably benzene or toluene until most of the water ofreaction is eliminated. A monoamine can also be used under certainconditions. The reaction temperature is less than 140° C. and alsoshould be below the boiling point of the phenol used but higher than theboiling point of the azeotroping agent. The vapor phase temperature liesbetween that of the water azeotrope and no higher than 95° C. As thewater of reaction and azeotroping agent are removed from the reactionmixture, quantities of the azeotroping agent are returned to thereaction mixture so as to maintain the temperature and reaction mixturevolume substantially constant. It is preferred that the process becontinuous with continuous removal of water and continuous return ofazeotroping agent. This is conveniently done by the use of aconventional Dean-Stark trap and condenser wherein after the azeotropecondenses, the water preferably sinks to the bottom of the trap forsubsequent removal and the azeotroping agent overflows the trap andreturns to the reaction mixture. Initially, the trap is filled withazeotroping agent.

The polyimide starting material prepared by the above-described processwill have the formula: ##STR8## wherein Ar and Ar' are as definedpreviously, ##STR9## n is 0 when X and X' are (1) or is a positiveinteger of at least one, preferably at least 4 and usually in the rangeof 4 to 20,

A is a terminal group which is --CH═CHR°, --C.tbd.CR°, --CN, --CHO,--OH, --NH₂ or --CH═NR" wherein R" is a monovalent aromatic organicradical (phenyl, naphthyl, etc.),

R is a hydrocarbon radical of 1 to 12 carbon atoms, and

R° is H or R.

When the monoamine is not used in the azeotroping process, the polyimidestarting material used in the present process will have two anhydrideend groups when the molar ratio of dianhydride to diamine in thereaction mixture is m + 1:m or two amine end groups when the molar ratioof dianhydride to diamine is m:m + 1 where m is a positive integer of atleast one and as high as n in the formula. Thus, the anhydrideterminated polyimide will have the formula: ##STR10## and the amineterminated polyimide can have the formula: ##STR11## In this latterevent R is also Ar.

When the molar ratio of dianhydride to diamine in the reaction mixtureis m + 1:m, two moles of a monoamine ARNH₂ can be added to the reactionmixture to provide the terminal groups (A), i.e., --CH═CHR°,--C.tbd.CR°, --CN, --CHO, OH and --CH═NR" wherein R" is a monovalentaromatic radical. R is from 1 to 20 (preferably 1 to 10) carbon atoms.Examples of suitable amines are H₂ NCH₂ CH═CH₂, H₂ N(CH₂)₆ CH═CH₂ H₂ NC₆H₄ CH═CH₂, H₂ NCH₂ C₆ H₄ CH═CH₂, H₂ NC₆ H₄ CH₂ CH═CH₂, H₂ N(CH₂)₃ C₆ H₄CH═CH₂, H₂ NC₆ H₄ C.tbd.CH, H₂ NCH₂ C.tbd.CH, H₂ NCH₂ CN, H₂ NCH₂CH═CHCN, H₂ NCH₂ C.tbd.CCN, H₂ NC₆ H₄ CN, H₂ NC₆ H₄ OH, H₂ NC₆ H₃(CH₃)CN, H₂ NC₆ H₄ CH₂ CN, H₂ NC₆ H₄ CH₂ OH, H₂ NCH₂ C₆ H.sub. 4 CN, H₂NCH₂ C₆ H₄ OH, H₂ NC₆ H₄ CH═CHCN, H₂ NC₁₀ H₇ CN, H₂ NC₁₀ H₇ OH, H₂ NCH₂C₆ H₄ CH₂ CN, H₂ NCH₂ C₆ H₄ CH₂ OH, H₂ NC₆ H₄ CHO, H₂ NC₆ H₄ CH₂ CHO, H₂NCH₂ C₆ H₄ CH₂ CHO, H₂ NCH₂ C₆ H₄ CHO, H₂ NC₆ H₄ CH═CHCHO, H₂ NC₆ H₄CH═NC₆ H₅, H₂ NC₆ H₄ CH₂ CH═NNC₆ H₄ CH₃. Preferred monoamines are allylamine, styryl amine, propargyl amine, aminobenzyl cyanide andaminobenzyl nitrile.

The chain-extending process used to make high molecular weightpolyimides will depend on the particular terminal groups present. Forexample, when the terminal groups are --CH═CHR°, --C.tbd.CR°, --CN or--CH═NR", chain extension occurs by the self-coupling of the startingpolyimide by heating, usually at a temperature in the range of about150°-450° C.

In particular, when the terminal groups are --CH═CH₂ such as when eitherallyl amine or styryl amine is used as the monoamine, chain extensionoccurs as in vinyl polymerization by thermal or free radical initiation.In this situation, any of the free radical polymerization catalysts canbe used, e.g., the peroxides such as benzoyl peroxide. A bis-maleimidecan also be copolymerized with the -CH═CH₂ terminated polyimides.Bis-maleimides are known in the art and have the formula: ##STR12##wherein Ar and Ar' are as defined previously, and n is 0 or a positiveinteger of 1 to 20.

These bis-maleimides can also be prepared by the azeotroping process ofmay aforesaid copending application Ser. No. 363,800 filed May 25, 1973.Other monovinyl or multivinyl monomers such as the acrylics, allylmethacrylate, ethylene dimethacrylate, styrene, maleic esters and thelike can also be copolymerized.

When the terminal groups are --C.tbd.CH, the polyimide can bechain-extended by catalytic polymerization in the presence of oxygenusing a cuprous salt, e.g., cuprous chloride, cuprous sulfate, cuprousacetate, etc. Generally, about 0.1 to 5% by weight of the catalyst issufficient.

Terminal groups which are --CN or --CH═NR" are polymerized using acatalytic amount of a Lewis acid salt, i.e., about 0.15 to 5 weightpercent of AlCl₃, SbCl₃, SbCl₅ or any others well-known as alkylation,isomerization or polymerization catalysts. For reasons of economy andhandling, zinc chloride, zinc sulfate and the copper salts are preferredas the coupling catalysts.

Chain extension can also occur by coupling the starting polyimide with acomplementary organic compound. The particular organic compound usedwill depend on the particular terminal groups. For example, when theterminal groups are --CH═CHR°, --C.tbd.CR°, --CN, --CHO, --CH.tbd.NR",one mole of the polyimide can be reacted with at least 3/4 mole(preferably 1-2 moles) of an aromatic bis-dipole of the formula Q--Ar--Qwherein Ar is a divalent aromatic radical (phenyl, napthyl, etc.) and Qis ##STR13## wherein R'" is an aliphatic or aromatic organic radical of1 to 12 carbon atoms, preferably an aromatic radical (e.g., --C₆ H₅,--C₆ H₄ (CH₃), etc.).

The chemistry of the monofunctional dipole compounds corresponding tothe difunctional dipoles used in the present process is well known inthe art. Syntheses of the monofunctional dipole compounds areexemplified by Rolf Huisgen, Angew. Chem. Vol 75 (No. 13), pages 604-637and 742-754, 1963, and in the Proceedings of the Chemical Society ofLondon, Oct. 1961, pages 351-369. Many of the difunctional dipoles usedin the present invention are synthesized by the same techniquesdescribed in these references as well as in U.S. Pat. Nos. 3,390,204,3,390,132 and 3,213,068. Preferred dipole compounds are1,4-benzenedinitrile oxide, 1,4-benzenedi(phenylnitrilimine) and1,4-benzenedi(phenylnitrile ylide).

To increase the rate of reaction between the polyimide and bis-dipole,the concentration of the bisdipole can be increased up to 2 moles. Thereaction can take place at ambient temperatures or slightly higher, butonce initiated, the temperature can go as high as the boiling point ofany solvent used, usually a phenol or the accepted aprotic polymersolvents disclosed in my copending application Ser. No. 363,799, filedMay 25, 1973 now U.S. Pat. No. 3,890,272.

The bis-maleimides described above are known to react with dipoles, butthe thermal stability of the resulting product is low. I have discoveredthat if polyimide character, i.e., ##STR14## is interjected between themaleimides, then the cycloaddition extension products have improvedthermal stability.

The reaction between the bis-dipolar compound and the reactive end groupis a 1,3-dipolar cycloaddition reaction which does not eliminateby-products during the course of propagation. For example, if styryl isthe reactive end group and 1,4-benzenedinitrile oxide is used as thedipolar compound, the mode of propagation can be shown as follows:##STR15##

When the terminal groups are --OH, the complementary organic compound isformaldehyde, a compound capable of generating formaldehyde under thereaction conditions such as paraformaldehyde or hexamethylene tetramine.The reaction is preferably carried out in the presence of lime as acatalyst with about 1 to 5 weight percent lime, based on the weight ofpolyimide, usually being sufficient. The amount of formaldehyde used asusually in the range of about 10 to 15% by weight, based on the weightof polyimide, but can range from about 5 to 25% by weight and evenhigher; however, there is usually no economic incentive for using higherconcentrations.

The dianhydride terminated polyimides are chain-extended by reactingthem with an aromatic diisocyanate of the formula Ar(NCO)₂ wherein Ar isa divalent aromatic organic radical preferably such as tolylene (CH₃ C₆H₃ <), xylylene (--CH₂ C₆ H₄ CH₂ --), benzylene (--C₆ H₄ CH₂ --),phenylene (C₆ H₄ <), naphthylene (C₁₀ H₆ <), diphenylene (C₁₂ H₈ <) andgenerally any of the other Ar radicals listed with the aromatic diaminesabove, to yield thermally stable foams under appropriate processingconditions.

The anhydride terminated polyimides can also be chain-extended byreacting them with any of the aromatic diamines previously described,preferably sulfonyl dianiline and oxydianiline, or by reacting them witha diamine terminated imide oligomer which can be prepared by myaforesaid application Ser. No. 363,800, filed May 25, 1973. Thisoligomer has the formula: ##STR16## wherein Ar and Ar' have been definedpreviously and,

n is a positive integer of at least 1, preferably 4 to 20.

The reaction of the diamine and diamine terminated oligomer with thedianhydride preferably can be carried out at a temperature above themelting point of the materials involved or preferably in the phenolsolvent defined previously, preferably m-cresol or a mixture of m-cresolwith its other isomers, as well as in any of the accepted aproticpolymer solvents mentioned previously.

The diamine terminal polyimides are chain-extended by reacting them withan anhydride of the formula ##STR17## wherein p is 2 or 3 and Ar' is anyof the radicals listed with the aromatic dianhydrides above when p is 2.When p is 3 Ar' is a hexavalent aromatic organic radical, the sixcarbonyl groups being attached directly to separate carbon atoms andeach pair of carbonyl groups being attached to adjacent carbon atoms inthe Ar' radical. Preferred anhydrides are mellitic dianhydride, mellitictrianhydride and 3,3',4,4'-benzophenonetetracarboxylic acid dianhydride.This reaction can be carried out at a temperature above the meltingpoint of the diamine terminated polyimide or preferably in any of thesolvents defined previously (preferably m-cresol or a mixture ofm-cresol and its isomers). Instead of the di- or trianhydride, itscorresponding tetra or hexa carboxylic acid can be used.

The chain-extension described above occurs by the reaction of theterminal --ArNH₂ groups in the polyimide oligomer with the anhydridegroups of the anhydride compound, with the formation of amic acidstructures ##STR18## This reaction preferably occurs by simply mixing asolution of the diamine terminated oligomer with a solution of theanhydride in the presence of a phenol of the structure ##STR19## whichhas been described previously. Since the two reactants are difunctional,it would be expected that propagation, i.e. chain-extension byend-coupling, would occur to such a degree that the viscosity wouldincrease to such an extent that the application of such mixed solutionswould be technically unfeasible or impractical.

Surprisingly, it has been discovered that when the anhydride compoundsare reacted with the polyimide oligomer in the presence of a phenol,there is only a slight increase in viscosity. This tends to indicatethat short chain lengths are formed such as exemplified by the followingstructure: ##STR20## where m represents the number of moles of thepolyimide and anhydride that have reacted -- perhaps only 1 to 2. Thus,the viscosity can remain constant for a long period of time. When thephenol is removed, for example by evaporation or distillation,chain-extension continues and the viscosity increases progressively asthe phenol is eliminated to give a value of m up to 100 or 1000 or more.However, when the anhydride and polyimide oligomer are reacted insolvents such as dimethyl formamide (DMF), dimethyl acetamide (DMAC),dimethyl sulfoxide (DMSO) and the like in the complete absence of aphenol, marked increases in viscosity are observed and unworkable gelsare obtained in some cases.

The mechanism by which the phenol exerts effective control on thechain-extending process is not completely understood but it seemsreasonable to assume that the phenol forms a complex with the diaminegroups of the polyimide and that the resulting anilinium phenateinactivates at least a portion of the terminal amine groups. Accordingto this theory, at least two moles of the phenol are required to complexwith one mole of the amine end-capped polyimide. However, since theequilibrium constant to the anilinium phenate side of the equationappears to be less than the constant to the reactant side, an excessover molar requirements of the phenol is preferred -- up to andincluding the use of the phenol as the sole solvent or medium in whichthe reaction is performed. When the reaction of the anhydride and thepolyimide oligomer is performed in a solvent or a liquid medium otherthan a phenol, then at least two moles, preferably 4-6 moles, of thephenol are used for each mole of the diamine end-capped polyimide.

Many advantages accrue to the use of the process of this invention,particularly to the control of viscosity per extent of solids content.One important advantage is that the amount of water of cyclization isreduced to the extent that n represents a closed ring which cannoteliminate water of reaction. Thus, films, laminates and molded or formedproducts of low or negligible porosity are obtained having good physicaland electrical properties.

The polyimides of the present invention have a number of uses. Theseinclude use of the solutions before curing as wire and insulatingvarnishes and to impregnate fabric substrates used in making flexibleand rigid electronic circuit boards and in making structural laminates.The solutions can be used to make fibers and films and as adhesives,particularly for film substrates, useful in aerospace and electronicsapplications. The powders can be used as molding powders and to makefibers, films and foams.

The invention can be further understood by the following examples inwhich parts and percentages are by weight unless otherwise indicated.

EXAMPLE 1 a. Preparation of Amine-Terminated Oligomeric Polyimide(BTAT-3). Reaction of BTCA and ODA (7:8).

An apparatus consisting of a 100 ml. three-neck, round-bottom flaskequipped with a magnetic stirrer, Dean-Stark trap and condensor, adropping funnel, heating mantle, etc. is used in this and numerousfollowing syntheses. For purposes of brevity, it will be called "them-cresol:benzene azeotropic apparatus."

In the m-cresol:benzene azeotropic apparatus was paced 4,4'-oxydianiline(ODA) (3.204 g., 0.016 mole) in 20 ml. of m-cresol and 10 ml. ofbenzene. After warming to 60° C., a solution of3,3',4,4'-benzophenonetetracarboxylic acid dianhydride (BTCA) (4.512 g.,0.014 mole) in 30 ml. m-cresol was added. A copious yellow precipitateformed immediately. The reaction mixture was heated to reflux and thesolid material dissolved, forming an orange solution. After 2 hours ofreflux, 0.30 ml. of water had been collected and a precipitate hadformed in the reaction flask. After cooling, the reaction mixture wasconcentrated on a rotary flash evaporator and then vacuum-dried at 170°C. to give 7.0960 g. (˜100%) of a yellow solid which was slightlysoluble in m-cresol, and insoluble in sulfolane and DMAC. On aFisher-Johns melting point apparatus it softened slightly at about 210°C., partially melted by 235° C., and rehardened to a granular solid at240° C.

Analysis: Calc'd. for C₂₁₅ H₁₁₀ N₁₆ O₄₃ : C, 72.18; H, 3.10; N, 5.48.Found: C, 70.26; H, 3.26; N, 6.11.

b. Preparation of Oligomeric Anhydride (BTOD-1). Reaction of BTCA andODA (2:1).

Into a 100 ml. three-neck round-bottom flask equipped with a magneticstirrer, thermometer, condenser, gas inlet tube, dropping funnel, etc.there was place, under nitrogen atmosphere, a solution of BTCA (6.444g., 0.02 mole) in 25 ml. of DMAC. Then, a solution of ODA (2.00 g., 0.01mole) in 15 ml. of DMAC was added over a period of 15 minutes. Thereaction, which was exothermic, was maintained at 40° C. during theaddition, following which it was heated at 85°-90° C. for 15 minutes. Tothis clear amber-colored solution, acetic anhydride (3.06 g., 0.03 mole)was added and the mixture was heated to 125° C. Within 15 minutes, ayellow precipitate formed. After heating, the reaction mixture for 1hour, the solvents were removed in a rotary flash evaporator. Theresidual light-yellow solid was washed with anhydrous ether and dried ina vacuum oven at 140° C., to afford a quantitative yield. It softenedslightly on a Fisher-Johns melting point apparatus at 120° C. and didnot melt when heated to 300° C. The product was soluble in m-cresol andN-methyl-2-pyrrolidone and only slightly soluble in boilingbenzonitrile, acetophenone or DMAC.

Its infrared spectrum shows the peaks for --C═O of the anhydride groupat 4.50 and 5.63μ, and for the imide C═O, at 5.82μ.

Analysis: Calc'd. for C₄₆ H₂₀ N₂ O₁₃ : C, 68.32; H, 2.49; N, 3.47.Found: C, 68.27; H, 2.82; N, 3.79.

c. Melt reaction of BTAT-3 and BTOD-1.

An intimate mixture of equimolar amounts of BTOD-1 and BTAT-3 was placedbetween glass plates and placed on a block preheated to 250° C. Thesample melted and rehardened within 3 minutes. Then, as the temperaturewas raised at 5° C./minute, the sample resoftened at 290° C., andrehardened at about 325° C.

EXAMPLE 2 a. Preparation of Foamed Polyimide (BTFM-1). Reaction ofBTOD-1 and Tolylene-2,4-diisocyanate (TDI) (1:1).

An intimate mixture of BTOD-1 prepared in Example 1 (b) (0.081 g.,0.0001 mole) and TDI (0.017 gl, 0.0001 mole) was prepared in a Wig-L-jigapparatus. A small sample of the mixture was placed between glass platesand placed onto a block preheated to 250° C. The entire sample melted,foamed and hardened within 1 minute.

b. Preparation of Foamed Polyimide (BTFM-2). Reaction of BTOD-1 and TDI(1:2).

An intimate mixture of BTOD-1 prepared in Example 1 (b) (0.81 g., 0.0001mole) and TDI (0.034 g., 0.0002 mole) was prepared in a Wig-L-jigapparatus. A small sample of the mixture was placed between glass platesand placed onto a block preheated to 250° C. The entire sample melted,foamed and hardened within 10 seconds. The volume increase wasnoticeably greater in this case than (a) above.

EXAMPLE 3 a. Preparation of Styrene-Terminated Oligomeric Polyimide(BTAS-4). Reaction of BTCA, DAPB-3,3, ODA and AS in 9:(4:4):2 MoleRatio.

In a large-scale m-cresol:benzene azeotropic apparatus was placed, undera slow nitrogen sweep, BTCA (21.7505 g. 0.0675 mole), 175 ml. ofm-cresol and 50 ml. of benzene. The mixture was warmed to approximately70° C. to dissolve the BTCA and then a solution of m-aminostyrene (AS)(1.7874 g., 0.015 mole) in 25 ml. of m-cresol, containing 0.1 g. oft-butyl catechol, was added over approximately 1/2 hour. The solutionwas then refluxed for 20 minutes. Then a solution of1,3-di(3-aminophenoxy)benzene (DAPB-3,3) (8.7699 g., 0.030 mole) and ODA(6.0072 g., 0.030 mole) in 75 ml. of m-cresol was added. Reflux wasmaintained for 3 hours; 2.47 ml. of water was collected. Then 50 ml. ofbenzene was distilled off.

After cooling to ambient temperature, the clear solution was addeddropwise to 600 ml. of well-stirred methanol. After stirring for 2hours, the solution was filtered. The isolated solid was heated in 200ml. of boiling methanol containing approximately 0.1 g. of t-butylcatechol for 1 hour and filtered. The methanol wash was repeated threetimes. A small portion of the solid was removed and treated in boilinginhibitor-free methanol. This small sample was used for testingpurposes, such as melting behavior, solubility, etc. The remainder ofthe material was vacuum-dried at ambient temperature for 40 hours, togive BTAS-4 as a yellow solid, 36.9 g. (103%). A TGA in nitrogen showeda loss of approximately 5% volatiles before an inflection point atapproximately 510° C. The sample was washed once more with hot methanoland vacuum-dried at 40° C. for 16 hours to give 35.3 g. (98%). A TGA innitrogen showed approximately 2% volatiles.

BTAS-4 was soluble in m-cresol and sulfolane, was partially soluble inhot DMAC and hot DMF, swelled slightly in dioxane, styrene, 75% DVB andchloroform, but was insoluble in methanol and benzene. When heated fromambient to higher temperatures on a Fisher-Johns melting point block,BTAS-4 softened at 185°-205° C., was partially molten at approximately220° C., was thick melt 235° C., and hardened after 20 minutes at 300°C. Its TGA in nitrogen showed an inflection point at approximately 510°C. and a 58% residue at 1000° C. The DTA displayed an endotherm(softening or melting) in the region of 190° C., which was followedimmediately by a strong exotherm (polymerization) in the region of190°-210° C., followed by a weak endotherm which blends into a secondmild exotherm at approximately 260° C. A 0.20 g. sample of BTAS-4 washeated in an air oven at 200° C. for 5 hours to give BTAS-4-H200. TheTGA of BTAS-4-H200 in nitrogen and in air showed the samples to besubstantially free of m-cresol. The inflection points in nitrogen and inair are almost identical in the 500° C. region; the difference innitrogen and in air is found in a char residue or 60% to 0%respectively, at temperatures higher than 600° C.

Analysis: Calc'd. for C₂₈₉ H₁₄₈ N₁₈ O₅₇ : C, 72.55; H, 3.12; N, 5.27; O,19.06. Found: C, 72.54; H, 3.20; N, 5.32; O, -----.

b. Reaction of BTAS-4 with ODA.

To a solution of BTAS-4 (0.4882 g., 0.0001 mole) in 14 ml. of m-cresolwas added a solution of ODA (0.020 g., 0.0001 mole) in 1 ml. ofm-cresol. The solutions were mixed in a small flask and placed in an airoven at 100° C. The temperature was raised slowly to 200° C. over aperiod of 6 hours to eliminate solvent and maintained at 200° C. for 24hours. The cured product was obtained as dark-brown chips. The productwas hard and tough, and required grinding in Wig-l-jig apparatus for 10minutes to produce a powder, which was vacuum-dried at 200° C. for 24hours, to give 0.5091 g. (100%). Its infrared spectrum (KBr disc) wasrecorded. Its TGA in nitrogen and in air showed, in both cases,inflection points in the region of 500° C. The product cured at 200° C.was insoluble in boiling m-cresol.

c. Thermal Polymerization of BTAS-4 in m-Cresol.

BTAS-4 (0.4882 g., 0.0001 mole) in 5 ml. of m-cresol was heatedaccording to the schedule given directly above to afford 0.4778 g. (98%)of dark glassy chips. Its infrared spectrum was recorded. Its TGA innitrogen showed an inflection point in the 500° C. region. The productcured at 200° C. is insoluble in boiling m-cresol.

d. Thermal Catalyzed Polymerization of BTAS-4.

BTAS-4 (0.4882 g., 0.0001 mole) and benzoyl peroxide (0.005 g.) in 5 ml.of m-cresol were heated according to the schedule given above. There wasobtained 0.4820 g. (99%) of a dark glassy solid. Its infrared spectrumwas similar to that of cured BTAS-4.

EXAMPLE 4 a. Preparation of Styrene-Terminated Oligomeric Polyimide(BTAS-9). Reaction of BTCA, DAPB-3,3, and AS in 9:8:2 Mole Ratio.

In an m-cresol:benzene azeotropic apparatus was placed, under a slownitrogen sweep, BTCA (2.175 g., 0.0675 mole), 10 ml. of m-cresol and 10ml. of benzene. The mixture was warmed to approximately 70° C. todissolve the BTCA and then a solution of AS (0.1787 g., 0.015 mole) in25 ml. of m-cresol, containing 0.1 g. of t-butyl catechol, was addedover approximately 1/2 hour. the solution was then refluxed for 20minutes. Then a solution of DAPB-3,3 (1.7540 g., 0.060 mole) in 7.5 ml.of m-cresol was added. Reflux was maintained for 3 hours and then 10 ml.of benzene was distilled off.

After cooling to ambient temperature, the clear solution was addeddropwise to 600 ml. of well-stirred methanol. After stirring for 2hours, the solution was filtered. The isolated solid was heated in 200ml. of boiling methanol containing approximately 0.1 g. of t-butylcatechol for 1 hour and filtered. The methanol wash was repeated threetimes. A small portion of the solid was removed and treated in boilinginhibitor-free methanol. This small sample was used for testingpurposes, such as melting behavior, solubility, etc. The remainder ofthe material was vacuum-dried at ambient temperature for 40 hours, togive BTAS-9 as a light-yellow solid, 3.6 g. (92%).

BTAS-9 was soluble in m-cresol, DMAC, DMF, sulfolane, dioxane,chloroform and methylene chloride; it was partially soluble in hottetrahydrofuran; it swelled in divinyl benzene, cis-1,2-dichloroethyleneand methyl methacrylate and was insoluble in methylethyl ketone andtrans-1,2-dichloroethylene. BTAS-9 melts in the 170°-205° C. range,thickens above 210° C. and rehardens at 230° C.

A small sample was vacuum dried at 200° C. to yield BTAS-9-H200 andanalyzed.

Analysis: Calc'd. for D₃₁₃ H₁₆₄ N₁₈ O₆₁ : C, 72.96; H, 3.21; N, 4.89; O,18.94. Found: C, 73.04; H, 3.39; N, 4.64; O, -----.

b. Catalyzed Polymerization of BTAS-9.

In a small beaker was placed a solution of the oligomer BTAS-9 (0.250g.) in 5 ml. of DMAC. Then there was added benzoyl peroxide (0.00259)and the solution was placed in an air oven at 100° C. for 24 hours. Thenthe temperature was raised to 200° C. over 8 hours and then maintainedat 200° C. for 60 hours. There was obtained a dark film (BTAS-9-cured).The polymer was insoluble in hot m-cresol.

EXAMPLE 5 a. Preparation of Styrene-Terminated Oligomeric Polyimide(NTAS-1). Reation of 1,4,5,8-Naphthalenetetracarboxylic Acid Dianhydride(NTCA), DAPB-3,3 and AS (9:8:2).

Using the m-cresol:benzene azeotropic apparatus procedure describedpreviously, there was allowed to react1,4,5,8-naphthalene-tetracarboxylic acid dianhydride (NTCA) (2.8369 g.,0.01125 mole), DAPB-3,3 (2.9233 g., 0.01 mole) and AS (0.2979 g., 0.0025mole). There was obtained NTAS-1, 4.4712 g. (79.1%) as a tan powderwhich partially melted, with darkening at 220°-260° C., rehardened at265° C., and then did not change up to 300° C. When a sample was placedon a Fisher-Johns apparatus at approximately 220° C., it becamecompletely molten by 260° C. and rehardened at about 265° C.

NTAS-1 was soluble in DMAC, m-cresol, sulfolane and concentratedsulfuric acid, and swelled in hot dioxane. Its infrared spectrum wasconsistent with that expected for the compound.

Analysis: Calc'd. for C₂₈₆ H₁₄₆ N₁₈ O₅₂ : C, 73.61; H, 3.15; N, 5.40; O,17.83. Found: C, 73.74; H, 3.50; N, 5.83; O, -----.

b. Catalyzed Polymerization of NTAS-1.

The oligomer, NTAS-1 (0.250 g.) in 5 ml. of DMAC was cured with benzoylperoxide (0.0025 g.) according to the schedule given in Example 4(b).There was obtained a dark granular solid (NTAS-1-cured). The polymer wasinsoluble in hot m-cresol.

EXAMPLE 6 a. Preparation of Nitrile-Terminated Oligomeric PolyimideBTAN-6. Reaction of BTCA, MDA-4,4 and AN (9:8:2).

In a m-cresol:benzene azeotropic apparatus was placed (2.1751 g., 0.0135mole) and 4-aminobenzonitrile (AN) (0.1772 g., 0.0030 mole) in 25 ml. ofm-cresol and 10 ml. of benzene. The mixture was brought to reflux andmaintained at reflux for 30 minutes. Then a solution of 4,4'-methylenedianiline (MDA-4,4) (1.1896 g., 0.0120 mole) in 15 ml. of m-cresol wasadded and the mixture was refluxed for 30 minutes. At the end of thereflux period the theoretical amount of water had been collected and thereaction mixture was a clear yellow solution. Then the reaction mixturewas added dropwise to approximately 100 ml. of methanol. Theprecipitated oligomer was digested three times in 100 ml. of hotmethanol, filtered and vacuum-dried at 70° C. for 24 hours. A paleyellow powder, BTAN-6, 2.1102 g. (94%) was obtained. On a Fisher-Johnsmelting point apparatus BTAN-6 melted over the range 230°-290° C. Thedrop melt was 270° C. It was soluble in m-cresol and sulfolane andbecame swollen in DMAC and dioxane.

b. Preparation of Nitrile-Terminated Oligomeric Polyimide BTAN-7.Reaction of BTCA, MDA-4,4, SDA-3,3 and AN (9:4+4:2).

According to the procedure reported in (a) above for the preparation ofBTAN-6, there was allowed to react BTCA (2.9001 g., 0.009 mole), MDA-4,4(0.7930 g., 0.004 mole), 3,3'-sulfonyldianiline (SDA-3,3) (0.9932 g.,0.004 mole) and AN (0.2363 g., 0.002 mole). The reaction mixture was aclear yellow solution at the end of a 3-hour reflux period. Afterprecipitation and vacuum-drying at 70° C. for 24 hours there wasobtained BTAN-7 as a pale yellow powder, 4.1594 g. (90.4%). On aFisher-Johns apparatus BTAN-7 melted over the range 255°-285° C. Thedrop melt was 260° C. BTAN-7 was soluble in m-cresol, sulfolane andDMAC.

c. Preparation of Nitrile-Terminated Oligomeric Polyimide BTAN-8.Reaction of BTCA, MDA-4,4, SDA-3,3 and AN (9:6+2:2).

The procedure reported in (a) above for the preparation of BTAN-6 wasrepeated except that BTCA (2.9001 g., 0.009 mole), MDA-4,4 (1.996 g.,0.006 mole), SDA-3,3 (0.4966 g., 0.002 mole), and AN (0.2363 g., 0.002mole) were allowed to react. The reaction mixture remained clearthroughout a 3-hour reflux period. After the usual isolation procedurethere was obtained BTAN-8 as a pale yellow powder, 4.2198 g. (94%) whichwas soluble in m-cresol and sulfolane. It became swollen in DMAC. On aFisher-Johns apparatus BTAN-8 melted over the range 240°-280° C. Thedrop melt was 265° C.

d. Preparation of Nitrile-Terminated Oligomeric Polyimide BTAN-9.Reaction of BTCA, MDA-4,4, SDA-3,3 and AN (9:7+1:2).

The procedure reported in (a) above for the preparation of BTAN-6 wasrepeated using BTCA (2.9001 g., 0.009 mole), MDA-4,4 (1.3878 g., 0.007mole), SDA-3,3 (0.2483 g., 0.001 mole) and AN (0.2363 g., 0.002 mole).The reaction mixture remained clear during a 3-hour reflux period. Therewas obtained BTAN-9 as a pale yellow powder, 4.1670 (94%) which wassoluble in m-cresol, partially soluble in hot sulfolane and insoluble inDMAC. On a Fisher-Johns apparatus BTAN-9 melted over the range 230°-290°C. The drop melt was 280° C.

e. Preparation of Nitrile-Terminated Oligomeric Polyimide BTAN-10.Reaction of BTCA, MDA-4,4, SDA-3,3 and AN (9:7.5+0.5:2).

The procedure reported in (a) above for the preparation of BTAN-6 wasrepeated using BTCA (2.9001 g., 0.009 mole), MDA-4,4 (0.4870 g., 0.0075mole), SDA-3,3 (0.1242 g., 0.0005 mole) and AN (0.2363 g., 0.002 mole).At the end of a 3-hour reflux period the reaction mixture was slightlyhazy. There was obtained BTAN-10 as a pale yellow powder, 4.1140 g.(93%), which was soluble in m-cresol, partially soluble in sulfolane andinsoluble in DMAC. On a Fisher-Johns apparatus BTAN-10 melted over therange 250°-280° C. The drop melt was 270° C.

f. Curing of Nitrile-Terminated Oligomeric Polyimides, BTAN-6 throughBTAN-10.

Intimate mixtures (˜0.25 g.) of each of the nitrile-terminatedoligomeric polyimides, BTAN-6 through BTAN-10 with Cu₂ Cl₂ (5% byweight) were prepared in a Wig-L-jig apparatus. A single mixture ofBTAN-6 with Cu₂ Cl₂ was prepared similarly. Then samples of each of themixtures were placed into a test tube, the tube was flushed withnitrogen and capped with a nitrogen-filled balloon. The tubes were thenplaced into a metal block preheated to and electronically maintained at300° C. After 2 hours the tubes were removed and allowed to cool. Thenthe TGA in air and in nitrogen of each of the samples was performed at10° C./minute on a Du Pont 900. The pertinent data for these reactionsare given in Table I.

                                      TABLE I                                     __________________________________________________________________________    Data on Curing of Nitrile-Terminated Oligomeric Polyimides BTAN-6 through     BTAN-10.                                                                                         TGA : Percent Residue at TGA                                     Weight   Weight                                                                            Atmos-                   Break                                                                             Inflec-                       Oligomer                                                                            (g.)                                                                              Catalyst                                                                           (g.)                                                                              phere                                                                              300° C.                                                                    400° C.                                                                    500° C.                                                                    600° C.                                                                    700° C.                                                                    ° C.                                                                       tion ° C.              __________________________________________________________________________    BTAN-6                                                                              0.250                                                                             Cu.sub.2 Cl.sub.2                                                                  0.0125                                                                             Air 100 95  0   0   0   365 --                                                N.sub.2                                                                           100 99  94      57  370 535                           BTAN-6                                                                              0.500                                                                             Cu.sub.2 Cl.sub.2                                                                  0.025                                                                              air 100 98  8   0   0   360 --                                                N.sub.2                                                                           100 99  95      59  370 550                           BTAN-7                                                                              0.250                                                                             Cu.sub.2 Cl.sub.2                                                                  0.0125                                                                             Air 100 98  0   0   0   350 --                                                N.sub.2                                                                           100 99  94      58  360 540                           BTAN-8                                                                              0.250                                                                             Cu.sub.2 Cl.sub.2                                                                  0.0125                                                                             Air 100 98  0   0   0   370 --                                                N.sub.2                                                                           100 99  94      62  370 550                           BTAN-9                                                                              0.250                                                                             Cu.sub.2 Cl.sub.2                                                                  0.0125                                                                             Air 100 88  0   0   0   340 --                                                N.sub.2                                                                           100 99  93      60  360 545                           BTAN-10                                                                             0.250                                                                             Cu.sub.2 Cl.sub.2                                                                  0.0125                                                                             Air 100 85  0   0   0   340 --                                                N.sub.2                                                                           100 99  94      57  350 555                           __________________________________________________________________________

EXAMPLE 7 A. Preparation of Amine Terminated Oligomers: a. Preparationof Amine-Terminated Oligomeric Polyimide (BTAT-4). Reaction of BTCA andSDA-3,3 (4:5).

In a m-cresol:benzene azeotropic apparatus was placed BTCA (11.2781 g.,0.035 mole), SDA-3,3 (10.8760 g., 0.0438 mole), 80 ml. of m-cresol and10 ml. of benzene. The mixture was refluxed for 31/2 hours during whichtime 1.3 ml. of water was collected. Then, the benzene was distilled offand the solution was precipitated in methanol. The precipitated oligomerwas digested three times in hot methanol and then vacuum dried at 70° C.for 24 hours to give BTAT-4, 19.7498 g. (95%) as a light-yellow solidwhich was soluble in m-cresol, DMAC and sulfolane. It swelled in hotdioxane. On a Fisher-Johns apparatus, it softened slightly above 180°C., melted at 245°-280° C. and rehardened after 5 minutes at 300° C. Thelowest temperature at which a sample would melt completely when droppedonto the preheated block was 270° C.

A sample was vacuum-dried at 200° C. and submitted for analysis.

Analysis: Calc'd. for C₁₂₈ H₆₈ N₁₀ O₃₀ S₅ : C, 64.42; H, 2.87; N, 5.87;O, 20.12; S, 6.72. Found: C, 63.71; H, 2.91; N, 5.75; O, -----; S, ----.

b. Preparation of Amine-Terminated Oligomeric Polyimide (BTAT-5).Reaction of BTCA and SDA-3,3 (8:9).

According to the procedure used in (a) above, there was allowed to reactBTCA (11.2781 g., 0.035 mole) and SDA-3,3 (9.7834 g., 0.0394 mole ) in80 ml. of m-cresol and 10 ml. of benzene. There was obtained theoligomer, BTAT-5, as a light-yellow solid, 18.3 g. (92.5%) which wassoluble in m-cresol, DMAC and sulfolane. It swelled in hot dioxane. On aFisher-Johns apparatus it began to melt at 255° C. but was notcompletely melted by 300° C., at which temperature it hardened in 3minutes. the lowest temperature at which a sample would melt completelywhen dropped onto the preheated block was 280° C.

The analysis was performed on a small sample vacuum-dried at 200° C.

Analysis: Calc'd. for C₂₄₄ H₁₂₄ N₁₈ O₅₈ S₉ : C, 64.77; H, 2.76; N, 5.57;O, 20.51; S, 6.38. Found: C, 63.54; H, 2.81; N, 5.45; O, -----; S, ----.

c. Preparation of Amine-Terminated Oligomeric Polyimide (BTAT-6).Reaction of BTCA and DAPB-3,3 (4:5).

According to the procedure in (a) above, BTCA (3.2223 g., 0.01 mole) andDAPB-3,3 (3.6529 g., 0.0125 mole) were allowed to react. There wasobtained BTAT-6, 6.1215 g. (94%) as a yellow powder. On a Fisher-Johnsmelting point apparatus BTAT-6 melted from 180°-200° C. and rehardenedafter 30 minutes at 300° C. The lowest temperature at which a samplecompletely melted when dropped onto a preheated block was 190° C. BTAT-6was soluble in m-cresol, DMAC, sulfolane and dioxane.

A sample was vacuum-dried at 200° C. for analysis.

Analysis: Calc'd. for C₁₅₈ H₈₈ N₁₀ O₃₀ :

C, 72.81; H, 3.40; N, 5.37; O, 18.42.

Found: C, 72.72; H, 3.35; N, 4.77; O, -----.

d. Preparation of Amine-Terminated Oligomeric Polyimide (BTAC-7).Reaction of BTCA and DAPB-3,3 (8:9).

According to the procedure in (a) above, BTCA (3.2223 g., 0.01 mole) andDAPB-3,3 (3.2887 g., 0.01125 mole) were allowed to react. There wasobtained BTAT-7 as a yellow powder, 5.8708 g. (95.4%). On a Fisher-Johnsapparatus BTAT-7 began to melt from 190° C. but did not completely meltby 300° C., when it hardened in 30 minutes. The lowest temperature atwhich a sample melted when dropped onto a preheated block was 220° C.BTAT-6 was soluble in m-cresol, DMAC, sulfolane and dioxane.

A small sample was vacuum-dried at 200° C. for analysis.

Analysis: Calc'd. for C₂₉₈ H₁₆₀ N₁₈ O₅₈ :

C, 72.74; H, 3.28; N, 5.12; O, 18.86.

Found: C, 72.45; H, 3.31; N, 5.04; O, -----.

B. Preparation of Anydride-Terminated Oligomers: a. Preparation ofAnhydride-Terminated Oligomeric Polyimide (BTOD-3). Reaction of BTCA andSDA-3,3 (5:4).

According to the procedure used in A(a) above, there was allowed toreact BTCA (12.0827 g., 0.375 mole) and SDA-3,3 (7.4493 g., 0.03 mole)in 80 ml. of m-cresol and 10 ml. of benzene. There was obtained theoligomer BTOD-3, as a light-yellow solid, 16.9 g. (92%) which wassoluble in m-cresol, DMAC, DMF and sulfolane. It softened at 240° C.,melted from 245°-265° C., with the evolution of small amounts of gas,and did not harden during 30 minutes at 300° C. The lowest temperatureat which a sample melted completely when dropped onto a preheated blockwas 255° C.

A small sample was vacuum-dried at 200° C. and submitted for analysis.

Analysis: Calc'd. for C₁₃₃ H₆₂ N₇ O₃₅ S₄ :

C, 65.30; H, 2.56; N, 4.01; O, 22.89; S, 5.24.

Found: C, 63.90; H, 2.74; N, 4.70; O, -----; S, ----.

b. Preparation of Anhydride-Terminated Oligomeric Polyimide (BTOD-4).Reaction of BTCA and SDA-3,3 (9:8).

According to the procedure used in A(a) above, there was allowed toreact BTCA (14.5003 g., 0.045 mole) and SDA-3,3 (9.9324 g., 0.04 mole)in 90 ml. of m-cresol and 20 ml. of benzene. There was obtained theoligomer, BTOD-4, as a light-yellow solid, 21.4 g. (95%) which wassoluble in m-cresol, DMAC, DMF and sulfolane. It began to melt at 265°C. with the evolution of small amounts of gas, but was not meltedcompletely by 300° C. and did not harden during 15 minutes at 300° C.The lowest temperature at which a sample melted completely when droppedonto a preheated block was 270° C.

A small sample vacuum-dried at 200° C. was submitted for analysis.

Analysis: Calc'd. for C₂₄₉ H₁₁₈ N₁₅ O₆₃ S₈ :

C, 65.24; H, 2.60; N, 4.58; O, 21.99; S, 5.60.

Found: C, 63.99; H, 2.73; N, 4.95; O, -----; S, ----.

c. Preparation of Anhydride-Terminated Oligomeric Polyimide (BTOD-5).Reaction of BTCA and DAPB-3,3 (5:4).

According to the procedure used in A(a) above, there was allowed toreact BTCA (4.0279 g., 0.0125 mole) and DAPB-3,3 (2.9223 g., 0.01 mole)in 40 ml. of m-cresol and 10 ml. of benzene. There was obtained theoligomer BTOD-5 (5.7678 g., 80%) as a light-yellow powder which wassoluble in m-cresol, DMAC, sulfolane and dioxane. On a Fisher-Johnsmelting point apparatus BTOD-5 melted over the range of 190°-205° C.with gas evolution and did not harden during 10 minutes at 300° C. Thelowest temperature at which a sample melted completely when dropped ontoa preheated block was 200° C.

Analysis: Calc'd. for C₁₅₇ H₇₈ N₈ O₃₅ :

C, 71.52; H, 2.98; N, 4.25; O, 21.24.

Found: C, 71.41; H, 3.21; N, 4.46; O, ----.

d. Preparation of Foamed Polymer by Reaction of a Diisocyanate and anOligomeric Anhydride Terminated Polyimide.

The procedure of Example 7B(c) was used to prepare an oligomer of BTCAand DAPB-3,3 in a 9:8 mole ratio (BTOD-20).

A mixture of oligomer (BTOD-20) (0.5495 g., 1 × 10⁴ mole) and TDI(0.0522 g., 3 × 10⁴ mole) was packed tightly into a pyrex tube. The tubewas then flushed well with nitrogen gas, and a balloon, which was filledwith nitrogen gas, was attached to the pyrex tube. The tube was theninserted into a thermostatically controlled metal block, preheated to225° C., causing the mixture to form a foamed structure within a fewminutes, which did not collapse when heating was continuted for 3 hours.A sample of the foamed product was insoluble in cold m-cresol butswelled in hot m-cresol. The foamed product was then heated at 300° C.in air over 2 hours whose TGA in air showed an inflection point in the525° C. region. In nitrogen the clear residue at 1000° C. amounted to60%.

C. Preparation of Polyimide Polymer Components:

Intimate mixtures of the various reactants prepared in A. and B. aboveand BTCA, SDA-3,3 and mellitic trianhydride (MTA) were prepared forpolymerization in a Wig-L-jig apparatus. The various polymers and theircomponents are listed in Table II.

                                      TABLE II                                    __________________________________________________________________________    Components Used in the Preparation of PIB-Type Polymers                       Components                                                                         Amine or Amine-                                                                          Anhydride or Anhydride-                                            Terminated Oligomer                                                                      Terminated Oligomer                                                                        Crosslinking Agent                               Polymer                                                                            (grams , moles)                                                                          (grams , moles)                                                                            (grams , moles)                                  __________________________________________________________________________         BTAT-4     BTOD-3                                                        PIB-1                                                                              0.2393 g., 0.0001 m                                                                      0.2446 g., 0.0001 m                                                                        none                                                  BTAT-4     BTOD-3       BTAT-4                                           PIB-1A                                                                             0.2393 g., 0.0001 m                                                                      0.2446 g., 0.0001 m                                                                        0.0239 g., 0.00001 m                                  BTAT-4     BT0D-3       BTAT-4                                           PIB-1B                                                                             0.2393 g., 0.0001 m                                                                      0.2446 g., 0.0001 m                                                                        0.1196 g., 0.00005 m                                  BTAT-4     BTOD-3       BTAT-4                                           PIB-1C                                                                             0.2393 g., 0.0001 m                                                                      0.2446 g., 0.0001 m                                                                        0.2393 g., 0.0001 m                                   BTAT-4     BTOD-3       SDA-3,3                                          PIB-1D                                                                             0.2393 g., 0.0001 m                                                                      0.2446 g., 0.0001 m                                                                        0.0025 g., 0.00001 m                                  BTAT-4     BTOD-3       SDA-3,3                                          PIB-1E                                                                             0.2393 g., 0.0001 m                                                                      0.2446 g., 0.0001 m                                                                        0.0125 g., 0.00005 m                                  BTAT-4     BTOD-3       SDA-3,3                                          PIB-1F                                                                             0.2393 g., 0.0001 m                                                                      0.2446 g., 0.0001 m                                                                        0.025 g., 0.0001 m                                    BTAT-5     BTOD-4                                                        PIB-2                                                                              0.2268 g., 0.00005 m                                                                     0.2289 g., 0.00005 m                                                                       none                                                  BTAT-5     BTOD-3                                                        PIB-3                                                                              0.4524 g., 0.0001 m                                                                      0.2446 g., 0.0001 m                                                                        none                                                  BTAT-4     BTOD-4                                                        PIB-4                                                                              0.2262 g., 0.00005 m                                                                     0.2290 g., 0.00005 m                                                                       none                                                  SDA-3,3    BTOD-3                                                        PIB-5                                                                              0.0496 g., 0.0002 m                                                                      0.4892 g., 0.0002 m                                                                        none                                                  SDA-3,3    BTOD-4                                                        PIB-6                                                                              0.0248 g., 0.0001 m                                                                      0.4584 g., 0.0001 m                                                                        none                                                  BTAT-4     BTCA                                                          PIB-7                                                                              0.4772 g., 0.0002 m                                                                      0.0644 g., 0.0002 m                                                                        none                                                  BTAT-5     BTCA                                                          PIB-8                                                                              0.4524 g., 0.0001 m                                                                      0.0322 g., 0.0001 m                                                                        none                                                  BTAT-4                  MTA                                              PIB-9                                                                              0.5011 g., 0.00021 m                                                                     none         0.0403 g., 0.00014 m                                  BTAT-5                  MTA                                              PIB-10                                                                             0.4072 g., 0.00009 m                                                                     none         0.0173 g., 0.00006 m                                  BTAT-6     BTOD-5                                                        PIB-11                                                                             0.2606 g., 0.0001 m                                                                      0.2636 g., 0.0001 m                                                                        none                                                  BTAT-7     BTOD-5                                                        PIB-12                                                                             0.2460 g., 0.00005 m                                                                     0.2476 g., 0.00005 m                                                                       none                                                  BTAT-7     BTOD-5                                                        PIB-13                                                                             0.4920 g., 0.0001 m                                                                      0.2636 g., 0.0001 m                                                                        none                                                  BTAT-6     BTOD-6                                                        PIB-14                                                                             0.2606 g., 0.0001 m                                                                      0.4952 g., 0.0001 m                                                                        none                                                  DAPB-3,3   BTOD-5                                                        PIB-15                                                                             0.0584 g., 0.0002 m                                                                      0.5272 g., 0.0002 m                                                                        none                                                  DAPB-3,3   BTOD-6                                                        PIB-16                                                                             0.1922 g., 0.0001 m                                                                      0.4952 g., 0.0001 m                                                                        none                                                  BTAT-6     BTCA                                                          PIB-17                                                                             0.5212 g., 0.0002 m                                                                      0.0664 g., 0.0002 m                                                                        none                                                  BTAT-7     BTCA                                                          PIB-18                                                                             0.4920 g., 0.0001 m                                                                      0.0322 g., 0.0001 m                                                                        none                                                  BTAT-6                  MTA                                              PIB-19                                                                             0.5212 g., 0.0002 m                                                                      none         0.0384 g., 0.000133 m                                 BTAT-7                  MTA                                              PIB-20                                                                             0.4920 g., 0.0001 m                                                                      none         0.0192 g., 0.000067 m                            __________________________________________________________________________

D. Preparation of Polyimides by Melt Reaction:

Small portions of the mixtures in C. above were placed between glassslides and then the slides were dropped onto a preheated, electronicallythermostatically controlled metal block. The samples were observed for15 minutes and then removed. Observations in melting behavior,rehardening and solubility in m-cresol are given in Table III. Then thetemperature of the metal block was raised and similar observations weremade both on the samples preheated for 15 minutes and on new samples.These observations are also given in Table III. The suffix M designatesthe polymer as prepared by a melt reaction.

                                      TABLE III                                   __________________________________________________________________________    Data and Observations on the Preparation of PIB-Type Polyimides by Melt       Reactions                                                                                    Observations                                                         T.sub.1 ° , T.sub. 2 °                                                                   (sample from T.sub.1 °)                                                                New Sample at                  Polymer                                                                             ° C                                                                             at T.sub.1 °                                                                           T.sub.2 °                                                                              T.sub.2 °               __________________________________________________________________________                   partial melt, hard in 2                                                                       partial melt, hard in 20                                                                      complete melt, hard in 3       PIB-1-M                                                                             265 , 300                                                                              min., swollen in hot m-                                                                       min., slightly swollen in                                                                     min., swollen in hot m-                       cresol          hot m-cresol    cresol                                        partial melt, hard in 5                                                                       partial melt, hard in 15                                                                      complete melt, hard in 5       PIB-2-M                                                                             265 , 300                                                                              min., swollen in hot m-                                                                       min., swollen in hot m-                                                                       min., swollen in hot m-                       cresol          cresol          cresol                                        slightly melted, rehardened                                                                   partial melt, hard in 20                                                                      complete melt, hard in 5       PIB-3-M                                                                             265 , 300                                                                              immediately, swollen in hot                                                                   min., swollen in hot m-                                                                       min., slightly swollen in                     m-cresol        cresol          hot m-cresol                                  complete melt with applied                                                                    partial melt, hard in 20                                                                      complete melt, hard in 5       PIB-4-M                                                                             265 , 300                                                                              pressure, hard in 10 min.,                                                                    min., swollen in hot m-                                                                       min., slightly swollen in                     soluble in hot m-cresol                                                                       cresol          hot m-cresol                                  complete melt, hard in 5                                                                      partial melt, hard in 15                                                                      complete melt, bubbled,                                                       hard                           PIB-5-M                                                                             265 , 300                                                                              min., swollen in hot m-                                                                       min., swollen in hot m-                                                                       in 15 min., swollen in                                                        hot                                           cresol          cresol          m-cresol                                      complete melt, hard in 5                                                                      partial melt, hard in 20                                                                      complete melt, bubbled,                                                       hard                           PIB-6-M                                                                             265 , 300                                                                              min., swollen in hot m-                                                                       min., swollen in hot m-                                                                       in 10 min., swollen in                                                        hot                                           cresol          cresol          m-cresol                                      complete melt, bubbled, hard                                                                  complete melt, bubbled, hard                                                                  complete melt, bubbled,                                                       hard                           PIB-7-M                                                                             265 , 300                                                                              in 5 min., partially solu-                                                                    in 25 min., swollen in hot                                                                    in 90 min., swollen in                                                        hot                                           ble in hot m-cresol                                                                           m-cresol        m-cresol                                      partial melt, hardened imme-                                                                  slow partial melt, hard in                                                                    complete melt, bubbled,                                                       hard                           PIB-8-M                                                                             265 , 300                                                                              diately, swollen in hot m-                                                                    25 min., slightly swollen                                                                     in 5 min., slightly                                                           swollen                                       cresol          hot m-cresol    in hot m-cresol                               partial melt, hard in 3                                                                       slight melt, hard in 5 min.,                                                                  partial melt, bubbled,                                                        hard                           PIB-9-M                                                                             265 , 300                                                                              min., swollen in hot m-                                                                       swollen in hot m-cresol                                                                       in 5 min., swollen in hot                     cresol                          m-cresol                                      partial melt, hard in 3                                                                       slight melt, hard in 5 min.,                                                                  partial melt, hard in 5        PIB-10-M                                                                            265 , 300                                                                              min., soluble in hot m-                                                                       swollen in hot m-cresol                                                                       min., swollen in hot m-                       cresol                          cresol                                        complete melt, bubbled,                                                                       softened, remained elastic                                                                    complete melt, bubbled,        PIB-11-M                                                                            225 , 300                                                                              hard in 15 min. for 90 min.     elastic for 90 min.                           complete melt, bubbled,                                                                       complete melt, bubbled,                                                                       complete melt, bubbled,        PIB-12-M                                                                            225 , 300                                                                              hard in 10 min. elastic for 90 min.                                                                           elastic for 90 min.                           complete melt, bubbled,                                                                       complete melt, remained                                                                       complete melt, bubbled,        PIB-13-M                                                                            225 , 300                                                                              hard in 20 min. elastic for 90 min.                                                                           elastic for 90 min.                           complete melt, bubbled,                                                                       complete melt, remained                                                                       complete melt, bubbled,        PIB-14-M                                                                            225 , 300                                                                              elastic, not hard in 1 hour                                                                   elastic for 90 min.                                                                           elastic for 90 min.                           complete melt, bubbled,                                                                       slightly melted, hard in                                                                      complete melt, bubbled,        PIB-15-M                                                                            225 , 300                                                                              hard in 6 min.  30 min.         hard in 20 min.                               complete melt, bubbled,                                                                       partial melt, bubbled,                                                                        complete melt, bubbled,        PIB-16-M                                                                            225 , 300                                                                              hard in 10 min. elastic for 90 min.                                                                           elastic for 90 min.                           complete melt, bubbled,                                                                       complete melt, few bubbles,                                                                   complete melt, bubbled,        PIB-17-M                                                                            225 , 300                                                                              hard in 40 min. elastic for 90 min.                                                                           elastic for 90 min.                           complete melt, bubbled,                                                                       complete melt, elastic for                                                                    complete melt, bubbled,        PIB-18-M                                                                            225 , 300                                                                              hard in 30 min. 90 min.         elastic for 30 min.                           complete melt, bubbled,                                                                       slightly melted, elastic                                                                      complete melt, few                                                            bubbles,                       PIB-19-M                                                                            225 , 300                                                                              hard in 1 hour  for 90 min.     hard in 30 min.                               complete melt, hard in                                                                        partial melt, hard in 1                                                                       complete melt, bubbled,        PIB-20-M                                                                            225 , 300                                                                              1 hour          hour            elastic for 2                  __________________________________________________________________________                                                   hours                      

E. Preparation of Polyimides By Solution Reactions:

Weighed samples (0.25 g.) of each of the mixtures prepared in C. abovewere added to 2.5 ml. of solvent and allowed to stand at ambienttemperature for 24 hours with occasional swirling. Then the samples weretreated to one of the heating schedules given below.

Heating Schedule A.

The solutions were heated in an air oven at 100° C. for 15 minutes.Precipitation did not occur. Then the samples were heated in an air ovenat 100° C. for 3 hours; then at 150° C. for 24 hours; and finally at200° C. for 24 hours. Then, small portions of the films obtained weredried in an air oven at 300° C. for 20 hours. The observations are givenin Table IV in which the suffix S designates the polymer as one preparedin solution. TGA data for selected PIB-type polyimides is given in TableV.

Heating Schedule B.

The solutions were heated at 50° C. for 30 minutes. Precipitation didnot occur. Then the samples were heated in a forced air oven at 40° C.for 20 hours, then at 100° C. for 4 hours. Then the samples were removedand a small piece of the film was chipped off. The chips were tested forsoftening or melting by placing them between glass slides and droppingthe assembly onto a metal block preheated to 180° C. These observationsare given in Table IV. Then the remainder of the films was heated at200° C. for 72 hours and then cooled. Observations on the products aregiven in Table IV. Suffix S indicates a solution reaction. TGA dataselected PIB-type polyimides is given in Table V.

                                      TABLE IV                                    __________________________________________________________________________    Data and Observations on the Preparation of PIB-Type                          Polyimides in Solution                                                                     Heating                                                          Polymer                                                                              Solvent                                                                             Schedule                                                                            Observations                                               __________________________________________________________________________    PIB-1-S                                                                              m-cresol                                                                            A     deep red smooth film, good adhesion to glass                                  vessel.                                                    PIB-1A-S                                                                             m-cresol                                                                            A     very dark red smooth film, better adhesion                                    to glass than PIB-1-S                                      PIB-1B-S                                                                             m-cresol                                                                            A     very dark red smooth film, better adhesion to                                 glass vessel than PIB-1-S                                  PIB-1C-S                                                                             m-cresol                                                                            A     very dark red smooth film, better adhesion                                    to glass vessel than PIB-1-S                               PIB-1D-S                                                                             m-cresol                                                                            A     very dark red smooth film, better adhesion                                    to glass vessel than PIB-1-S                               PIB-1E-S                                                                             m-cresol                                                                            A     very dark red smooth film, better adhesion                                    to glass vessel than -PIB-1F-S m-cresol A very dank                           red smooth film, less adhesion                                                to glass vessel than PIB-1-S                               PIB-2-S                                                                              m-cresol                                                                            A     deep red smooth film, good adhesion to                                        glass vessel                                               PIB-3-S                                                                              m-cresol                                                                            A     deep red smooth film, good adhesion to                                        glass vessel                                               PIB-4-S                                                                              m-cresol                                                                            A     lighter red smooth film, good adhesion                                        to glass vessel                                            PIB-5-S                                                                              m-cresol                                                                            A     deep red smooth film, good adhesion to                                        glass vessel                                               PIB-6-S                                                                              m-cresol                                                                            A     lighter red smooth film, good adhesion to                                     glass vessel                                               PIB-7-S                                                                              m-cresol                                                                            A     lighter red smooth film, good adhesion to                                     glass vessel                                               PIB-8-S                                                                              m-cresol                                                                            A     very deep red smooth film, good adhesion                                      to glass vessel                                            PIB-9-S                                                                              m-cresol                                                                            A     dark-brown smooth film, good adhesion to                                      glass vessel                                               PIB-10-S                                                                             m-cresol                                                                            A     dark-brown smooth film, with small amount of                                  very fine particles, good adhesion to glass                                   vessel                                                     PIB-11-S                                                                             dioxane                                                                             B     H100: good yellow film; H180: melted,                                         bubbled, hardened in 10 sec.; H200: foamed,                                   tough film                                                 PIB-12-S                                                                             dioxane                                                                             B     H100: some solid in yellow film; H180: -   melted,                            bubbled, hardened in 20 min.; H200:                                           foamed, tough film                                         PIB-13-S                                                                             dioxane                                                                             B     H100: some solid in yellow film; H180:                                        melted, bubbled, hardened in 1 min.; H200:                                    foamed, tough film                                         PIB-14-S                                                                             dioxane                                                                             B     H100: good yellow film; H180: melted,                                         bubbled, hardened in 1 min.; H200: foamed,                                    tough film                                                 PIB-15-S                                                                             dioxane                                                                             B     H100: good yellow film; H180: melted,                                         bubbled, hardened in 1 min.; H200: foamed,                                    tough film                                                 PIB-16-S                                                                             dioxane                                                                             B     H100: good yellow film; H180: melted,                                         bubbled, hardened in 1 min.; H200: foamed,                                    tough film                                                 PIB-17-S                                                                             dioxane                                                                             B     H100: good yellow film; H180: melted,                                         bubbled, hardened in 1 min.; H200: foamed,                                    tough film                                                 PIB-18-S                                                                             dioxane                                                                             B     H100: good yellow film; H180: melted,                                         bubbled, hardened in 1 min.; H200: foamed,                                    tough film                                                 PIB-19-S                                                                             dioxane                                                                             B     solution gelled in 1/2 hr.; H100: good yellow                                 film; H180: softened, not hard in 1 hr.;                                      H200: few bubbles, tough film                              PIB-20-S                                                                             dioxane                                                                             B     solution gelled in 1/2 hr.; H100: good yellow                                 film; H180: softened, not hard in 1 hr.:                                      H200: few bubbles, tough film                              __________________________________________________________________________

                                      TABLE V                                     __________________________________________________________________________    TGA Data for Selected PIB-Type Polyimides                                            Atmos-                                                                            TGA: Percent Residue at                                            Polymer                                                                              phere                                                                             200° C                                                                      300° C                                                                      400° C                                                                      500° C                                                                      600° C                                                                      700° C                                                                      800° C                        __________________________________________________________________________    PIB-1-S                                                                              Air 100   98  94   89   67   0    0                                    PIB-1F-S                                                                             Air 100   99  95   92   73   0    0                                    PIB-4-S                                                                              Air 100  100  97   89   70   12   0                                    PIB-8-S                                                                              Air 100  100  97   93   78   0    0                                    PIB-9-S                                                                              Air 100   98  92   89   70   0    0                                    PIB-11-S                                                                             Air 100  100   99+ 99   76   0    0                                    PIB-17-S                                                                             Air 100  100  99   98   83   10   0                                    PIB-19-S                                                                             Air 100  100  98   97   82   13   0                                    __________________________________________________________________________

F. Coating of Substrates:

Solutions PIB-17-S and PIB-19-S were coated on various substrates eitherby applying the solution with a small camel's hair brush or by dipping,and then cured by heating the coated articles in a forced air oven at80° C. for 20 hours, 100°-110° C. for 3 hours and then 200° C. for 20hours. Substrates coated were stainless steel and aluminum panels, 100pores/inch and 20 pores/inch reticulated polyurethane foam, 1.5 oz./ft.²random glass mat, coppe wire No. 24, wood dowel (charred during cure),and asbestos board. Bubbling occurred on the surface of many of thesamples prepared from PIB-17-S. Very little bubbling occurred to thecoatings prepared from PIB-19-S.

Example 8 a. Synthesis of Propargyl-Terminated Oligomeric Polyimide(BTPA-1). Reaction of BTCA, ODA and Propargyl Amine (2:1:2).

In a m-cresol:benzene azeotropic apparatus was placed in a solution ofBTCA (29.001 g., 0.09 mole) in 200 ml. of m-cresol and 50 ml. ofbenzene. The mixture was warmed to approximately 50° C. and a solutionof ODA (9.011 g., 0.045 mole) in 150 ml. of m-cresol was added, forminga slight amount of yellow precipitate. After 10 minutes, a solution ofpropargyl amine (5 g., 0.908 mole) in 50 ml. of m-cresol was added andthe solution heated to reflux. During 2 hours of reflux, 3.3 ml. ofwater was collected. After cooling, the deep red solution wasconcentrated on a rotary flash evaporator. A small sample was removedfor analysis and approximately 5 mg. of t-butyl catechol was added tothe bulk of the residue, which was vacuum-dried at 100° C. for 30 hours,and then at 150° C. for 12 hours, to give sample A, 37.850 g. (95%) as adark-brown solid. It softened at 270° C.; partially melted between280°-300° C., but quickly rehardened at 300° C.

Analysis: Calc'd. for C₅₂ H₂₆ N₄ O₁₁ :

C, 70.75; H, 2.97; N, 6.35; O, 19.94.

Found: C, 70.84; H, 3.13; N, 6.31; O, -----.

b. Polymerization of BTPA-1.

A sample of BTPA-1 was mixed with about 5% by weight of Cu₂ Cl₂ (cuprouschloride) and spread on a hot plate preheated to the melting point ofthe BTPA-1. The sample was open to air. An infusible, insoluble polymerwas obtained due to the oxygen coupling of the acetylene terminalgroups.

EXAMPLE 9 a. Preparation of Phenolic-Terminated Oligomeric Polyimide(BTAP-1). Reaction of BTCA, ODA and p-Aminophenol (2:1:2).

In the m-cresol:benzene azeotropic apparatus was placed a solution ofBTCA (3.222 g., 0.01 mole) in 25 ml. of m-cresol and 15 ml. of benzene.After warming to 50° C., a solution of ODA (1.001 g., 0.005 mole) in 15ml. of m-cresol was added, forming an immediate yellow precipitate.Further heating did not dissolve the precipitate, and, after 10 minutes,a slurry of freshly purified p-aminophenol (m.p. 190°-193° C.; 1.019 g.,0.01 mole) in 10 ml. of m-cresol was added. At reflux, the soliddissolved forming an orange solution. During 2 hours of reflux, 0.20 ml.of water was collected and a precipitate formed. Then, the solvents wereremoved on a rotary flash evaporator and the residue was vacuum-dried at170° C., yielding a yellow solid, 4.907 g. (99%). Its infrared spectrumwas consistent with the structure expected for the compound. It softenedslightly at 50° C., was almost completely melted at 265° -280° C.; andrehardened at 283° C. It was soluble in hot m-cresol, hot DMAC and hotsulfolane.

Analysis: Calc'd. for C₅₈ H₃₀ N₄ O₁₃ :

C, 70.30; H, 3.05; N, 5.65; O, 20.99.

Found: C, 70.04; H, 3.01; N, 5.73; O, -----.

b. Polymerization of BTAP-1.

A mixture of BTAP-1 with about 10-12% paraformaldehyde and 1-5% limecures into an insoluble, intractable polymer when heated at the meltingpoint of BTAP-1 on a hot plate.

EXAMPLE 10 a. Preparation of Phenol-Terminated Oligomeric Polyimide(BTAP-4). Reaction of BTCA, SDA-3,3 and p-Aminophenol (5:4:2).

According to the m-cresol:benzene technique there was allowed to reactBTCA (6.4446 g., 0.02 mole), SDA-3,3 (3.9730 g., 0.016 mole) andp-aminophenol (0.8730 g., 0.008 mole). There was obtained 10.0418 g.(95%) of a pale yellow powder (BTAP-4) which was soluble in m-cresol,DMAC and sulfolane. In hot dioxane BTAP-4 formed a separate oily layer.On a Fisher-Johns melting point apparatus BTAP-4 softened at 210° C.,melted at 240°-260° C. and did not harden on being heated at 300° C. for40 minutes. The lowest temperature at which a sample would meltcompletely when dropped onto the preheated stage was 250° C.

Analysis: Calc'd. for C₁₄₅ H₇₂ N₁₀ O₃₅ S₄ :

C, 65.90; H, 2.75; N, 5.30; O, 21.19; S, 4.85.

Found: C, 65.45; H, 2.88; N, 4.99; O, -----; S, ----.

C, 65.43; H, 2.95; N, 5.31; O, -----; S, ----.

b. Polymerization of BTAP-4.

A mixture of BTAP-4 with about 10-12% paraformaldehyde and 1-5% limecures into an insoluble, intractable polymer when heated at the meltingpoint of BTAP-4 on a hot plate.

c. Preparation of Aldehyde-Terminated Oligomer.

When an equivalent molar quantity of p-aminobenzaldehyde, NH₂ C₆ H₄ CHO(0.968 g.) is used instead of the p-aminophenol of (a) of this Example,the corresponding aldehyde-terminated oligomeric imide is obtained.

Similarly, when an equivalent molar amount ofp-aminobenzylidene-aniline, NH₂ C₆ H₄ CH═NC₆ H₅ (1.568 g.) is usedinstead of the p-aminophenol of (a) of this Example, the correspondingSchiff base-terminated oligomer is obtained. The amino-aryl Schiff baseswere readily prepared by the procedure give by Rossi in Gazz, chim.,Ital., 44, 263 (1966).

d. Coupling of Schiff Base-Terminated Oligomer.

The Schiff base-terminated oligomers as in (c) of this Example couplesimilarly to the nitrile terminated oligomers of Example 6. They couplereadily when heated in the range of 200°-300° C. for 30 minutes to 2hours, depending on the nature of the oligomer and of the Schiff basetermini. The coupling reaction is accelerated markedly by the additionof catalytic quantities of Lewis acid salts, from about 0.15 to about 3weight percent, such as AlCl₃, SbCl₃, SbCl₅ or any of the numerous Lewisacid salts well-known as alkylation, isomerization or polymerizationcatalysts. For reasons of economy and relative ease of handling, zincchloride, zinc sulfate, and the copper salts are preferred as couplingcatalysts for the Schiff base-terminated oligomeric polyimides.

EXAMPLES 11-56 A. Preparation of Imide Oligomers a. Preparation ofAromatic Nitrile-Terminated Oligomeric Polyimide (BTAN-2). Reaction of3,3',4,4'-Benzophenonetetracarboxylic Acid Dianhydride (BTCA),4,4'-Oxydianiline (ODA) and 4-Aminobenzonitrile (AN) (2:1:1).

In the m-cresol:benzene azeotropic apparatus there was placed a solutionof 3,3',4,4'-benzophenonetetracarboxylic acid dianhydride (BTCA) (3.222g., 0.01 mole) in 25 ml. m-cresol and 15 ml. benzene. The mixture waswarmed to approximately 50° C. and a solution of 4,4'-oxydianiline (ODA)(1.001 g., 0.005 mole) in 15 ml. of m-cresol was added, giving animmediate yellow precipitate. After 15 minutes, a solution of4-aminobenzonitrile (AN) (1.299 g., 0.011 mole) in 10 ml. of m-cresolwas added. During 2 hours of refluxing, the solution became orange and0.25 ml of water was collected. Precipitation did not occur. Aftercooling, the solvents were removed on a rotary flash evaporator and theresidue was vacuum-dried at 100° C. to yield 5.177 g. (102%) ofphenylnitrile-terminated oligomeric polyimide based on BTCA (BTAN-2). Ona Fisher-Johns melting point apparatus, 230° C. was the lowesttemperature at which it softened before rehardening immediately. It wassoluble in hot m-cresol, slightly soluble in hot dimethyl acetamide(DMAC), and insoluble in hot acetone. A sample of BTAN-2 was postheatedin nitrogen at 300° C. for 24 hours, and its TGA in nitrogen of sampleBTAN-2-H300, showed an inflection point at 410° C.

Analysis: Calc'd. for C₆₀ H₂₈ N₆ O₁₁ :

C, 71.43; H, 2.80; N, 8.03; O, 17.44

Found: C, 70.83; H, 2.81; N, 7.77; O, -----.

Found: C, 71.22; H, 2.86; N, 7.93; O, ----- (dried at 140° C.)

b. Preparation of Aromatic Nitrile-Terminated Oligomeric Polyimide(BTAN-3). Reaction of BTCA, 3,3'-Sulfonyldianiline (SDA-3,3), and AN(9:8:2).

In the m-cresol:benzene azeotropic apparatus there was placed a solutionof BTCA; (2.1750 g., 0.00675 mole) in 25 ml. of m-cresol and 10 ml. ofbenzene. The solution was warmed to approximately 70° C. and a solutionof AN (0.1773 g., 0.0015 mole) in 10 ml of m-cresol was added over about20 minutes. After stirring at approximately 70° C. for 15 minutes, asolution of 3,3'-sulfonyldianiline (SDA-3,3) (1.4899 g., 0.0060 mole) in15 ml. of m-cresol was added and the solution was heated to reflux for 3hours, during which time, 0.3 ml. of water was collected; then thebenzene was distilled off and after cooling to room temperature, thesolution was added dropwise slowly to 200 ml. of well-stirred methanol,to yield a light-yellow solid. The solid was filtered off, digested fourtimes in hot methanol, and dried at 40° C. for 24 hours, to give 3.40 g.(95%) of yellow product. The yield, corrected for about 2% retainedm-cresol, was 93.5%. The oligomer partially melted at 255° C. andrehardened at 275° C.; it was soluble in m-cresol, DMAC and hotsulfolane, but insoluble in dioxane. A small sample, vacuum-dried at200° C. for 4 hours, showed a 2% loss of m-cresol, which was confirmedin its TGA in nitrogen, which also shows an inflection point in nitrogenin the 500° C. region. Its DTA in nitrogen shows an endotherm at 225° C.

Analysis: Calc'd. for C₂₆₃ H₁₂₆ N₂₀ O₆₁ S₈ :

C, 65.83; H, 2.65; N, 5.84; O, 20.34; S, 5.35.

Found: C, 65.29; H, 2.70; N, 5.36; O, -----; S, ----.

The above procedure was repeated except that the quantities used wereincreased to yield 33.0 g. (97%) of BTAN-3. The quantities used wereBTCA, 21.7505 g., 0.0675 mole; SDA-3,3, 14.899 g., 0.060 mole; AN,1.7172 g., 0.0150 mole.

c. Preparation of Aromatic Nitrile-Terminated Oligomeric Polyimide(BTAN-4). Reaction of BTCA, 1,3-Di(3-Aminophenoxy)benzene (DAPB-3,3) andAN (9:8:2).

In the m-cresol:benzene azeotropic apparatus there was placed a solutionof BTCA (2.1753 g., 0.00675 mole) in 25 ml. of m-cresol and 10 ml ofbenzene. The solution was warmed to approximately 70° C. and a solutionof AN (0.1773 g. 0.0015 mole) in 10 ml. of m-cresol was added over about20 minutes. After stirring for another 15 minutes, a solution of1,3-di(3-aminophenoxy)benzene (DAPB-3,3) (1.7540 g., 0.0060 mole) in 15ml of m-cresol was added. The solution was heated to reflux for 3 hoursand 0.2 ml of water was collected. Then the benzene was distilled off.After cooling, the clear solution was added dropwise to 200 ml ofmethanol. The precipitated solid was digested three times in hotmethanol and vacuum-dried at 70° C. to give BTAN-4, as a light-yellowsolid, 3,4 g. (88%).

The infrared spectrum (KBr disc) of BTAN-4 is given in FIG. 29; it wassoluble in m-cresol, DMAC, sulfolane, dioxane; because a paste inmethylene chlordie, swelled in chloroform and was insoluble inacetonitrile. BTAN-4 softened at 180° C., melted over the range of197°-218° C., thickened above 290° C., but did not harden within 20minutes at 300° C., although it did darken somewhat. For the sampledried at 70° C., the DTA in nitrogen showed a melting endotherm at about180° C.

A sample of BTAN-4, vacuum-dried at 200° C., to eliminate volatiles, wassubmitted for analysis.

Analysis: Calc'd. for C₃₀₅ H₁₅₈ N₂₀ O₆₁ :

C, 72.13; H, 3.14; N, 5.52; O, 19.22.

Found: C, 72.41; H, 3.28; N, 5.11; O, -----.

d. Synthesis of Allyl-Terminated Oligomeric Polyimide (BTAA-3). Reactionof BTCA, ODA and Allylamine (2:1:2).

In the m-cresol:benzene azeotropic apparatus, there was placed asolution of BTCA (3.222 g., 0.01 mole) in 25 ml. of m-cresol and 15 ml.of benzene. The solution was warmed to approximately 60° C. and asolution of ODA (1.001 g., 0.005 mole) in 15 ml. of m-cresol was added,forming an immediate yellow precipitate which dissolved on heatingfurther for 5 minutes. Then, a solution of allylamine (0.629 g., 0.011mole) in 10 ml of m-cresol was added, after which the solution washeated to reflux; during 2 hours of reflux 0.25 ml. of water wascollected. After cooling, the solution was made up to 80 ml. with addedbenzene, and it was divided into two 40-ml. portions.

The first 40-ml. fraction was added to 250 ml. of methanol and thenstirred for 1 hour. This solid material was isolated by centrifuging anddried in a vacuum oven at 80° C. for 36 hours, yielding a yellow solid(A), 1.87 g. (84%).

The second 40-ml. fraction was evaporated on a rotary flash evaporatorand the residue was dried in a vacuum oven at 80° C., yielding a yellowsolid (B), 2.306 g. (104%). Sample B softened at 130° C., was nearlycompletely molten at 200°-300° C., darkened in 10 minutes at 230° C.,was soluble in hot m-cresol, slightly soluble in hot DMAC, and insolublein acetone.

Analysis: Calc'd. for C₅₂ H₃₀ N₄ O₁₁ : C, 70.42; H, 3.41; N, 6.32; O,19.85. Found: C, 70.99; H, 3.79; N, 6.47; O, -----.

A sample of BTAA-3B was postheated in nitrogen at 300° C. for 24 hours,and its TGA in nitrogen, at 10° C./minute, showed an inflection point at360° C.

e. Preparation of Aliphatic Nitrile-Terminated Oligomeric Polyimide(BTBN-1). Reaction of BTCA, ODA and 4-Aminobenzyl Cyanide (BN) (2:1:2).

In the m-cresol:benzene azeotropic apparatus was placed a solution ofBTCA (3.222 g., 0.01 mole) in 25 ml. m-cresol and 15 ml. of benzene. Themixture was warmed to approximately 50° C. and a solution of ODA (1.001g., 0.005 mole) in 15 ml. of m-cresol was added, giving an immediateyellow precipitate. After refluxing for 15 minutes, a solution ofaminobenzyl cyanide (BN) (1.454 g., 0.011 mole) in 10 ml. of m-cresolwas added. The precipitate dissolved quickly. During 11/2 hours ofreflux, 0.30 ml. of water was collected and a precipitate formed. Thensodium acetate (0.041 g., 0.0005 mole) was added and reflux wascontinued for another hour, and another 0.05 ml. of water was collected.After cooling, the solvents were removed on a rotary flash evaporatorand the residue dried in a vacuum oven at 100° C., the yield was 5.170g. (˜100%). Its infrared spectrum was consistent with the expectedstructure. Benzylcyanide-terminated oligomeric polyimide based on BTCA(BTBN-1) softened at 200° C., was almost completely melted by 290° C.and rehardened rapidly at 300° C. Also, it was soluble in hot m-cresol,slightly soluble in hot DMAC, and insoluble in acetone. A sample driedat 300° C. was also submitted for analysis.

Analysis: Calc'd. for C₆₂ H₃₂ N₆ O₁₁ : C, 71.81; H, 3.11; N, 8.11; O,16.97. Found (B): C, 70.28; H, 3.22; N, 8.12; O, -----. (dried at 300°C.)

The TGA in nitrogen on the sample dried at 300° C. showed an inflectionpoint of 360° C. f. Preparation of Aliphatic Nitrile-TerminatedOligomeric Polyimide (BTBN-3). Reaction of BTCA, SDA-3,3 and BN (9:8:2).

According to the azeotropic procedure used in (b) above, BTCA (2.1752g., 0.00675 mole), BN (0.1982 g., 0.0015 mole) and SDA-3,3 (1.4898 g.,0.0060 mole) were allowed to react. There was obtained 3.27 g. (91%) ofa light-yellow solid (BTBN-3). The yield, corrected for approximately 1%retained m-cresol, was 89%.

The oligomer melted at 250-26° C., and rehardened at 290° C. It wassoluble in m-cresol, DMAC and hot sulfonlane but insoluble in dioxane.

A small portion, vacuum-dried at 200° C. for 4 hours showed at 1% lossof retained m-cresol, which was confirmed in its TGA in nitrogen whichalso showed an inflection point in the 500° C. region.

The above procedure was repeated except that the quantities used weresuch as to yield a larger amount of product: BTCA, 21.750 g., 0.0675mole; SDA-3,3, 14.899 g., 0.060 mole; BN, 1.982 g., 0.0150 mole. TheBTBN-3 obtained from this reaction amounted to 34.8 g. (96%).

Analysis: Calc'd. for C₂₆₅ H₁₃₀ N₂₀ O₆₁ S₈ : C, 65.94; H, 2.72; N, 5.80;O, 20.22; S, 5.32. Found: C, 65.18; H, 2.65; N, 5.71; O, -----; S,----.

g. Preparation of Aliphatic Nitrile-Terminated Oligomeric Polyimide(BTBN-4). Reaction of BTCA, DAPB-3,3 and BN (9:8:2).

According to the procedure used in (c) above to prepare BTAN-4, BTCA(2.1753 g., 0.00675 mole), BN (0.1982 g., 0.0015 mole) and DAPB-3,3(1.7540 g., 0.0060 mole) were allowed to react to afford, aftervacuum-drying at 70° C., BTBN-4, 3.8 g. (97%) as a light-yellow solid.BTBN-4 was soluble in m-cresol, DMAC, sulfolane and dioxane. It waspartially soluble in hot chloroform and hot methylene chloride, and wasinsoluble in acetonitrile.

On a Fisher-Johns melting point apparatus, BTBN-4 softened at 135° C.,melted at 196°-215° C., thickened above 235° C. and remelted at 255° C.It did not reharden when held for 1/2 hour at 300° C. A sample ofBTBN-4, vacuum-dried at 200° C., was submitted for analysis.

Analysis: Calc'd. for C₃₀₇ H₁₆₂ N₂₀ O₆₁ :

C, 72.20; H, 3.20; N, 5.49; O, 19.11. Found: C, 72.21; H, 3.15; N, 5.44;O, -----.

h. Preparation of Styrene-Terminated Oligomeric Polyimide (BTAS-1).Reaction of BTCA, ODA and m-Aminostyrene (AS) (2:1:2).

In the m-cresol:benzene azeotropic apparatus was placed a solution ofBTCA (3.222 g., 0.01 mole) in 25 ml. of m-cresol and 10 ml. of benzene.After warming to approximately 70° C., a solution of ODA (1.001 g.,0.005 mole) in 15 ml of m-cresol containing 2 mg. of t-butyl catecholwas added, forming an immediate yellow precipitate. After heating for 15minutes, a solution of m-aminostyrene (AS) (1.192 g., 0.01 mole, SaponLaboratories) in 10 ml. of m-cresol was added and the solution washeated to reflux, forming a homogeneous solution. After 1 hour ofreflux, a precipitate began to form. After 2 hours of reflux, duringwhich 0.25 ml. of water was collected, the reaction mixture was cooledand poured into 250 ml. of methanol. After stirring for several hours,the solid material was filtered off, washed with methanol andvacuum-dried at 40° C. for 18 hours. The sample still had a distinctodor of m-cresol. A small portion was removed and vacuum-dried at 200°C. for 24 hours to give fraction A whose infrared spectrum was recorded.The remainder of the material was finely divided and stirred with 50 ml.of ether, and dried at 40° C to afford 4.0402 g. (80%) of a yellowpowder, fraction B. The infrared spectrum of sample A was substantiallythe same as that of sample B.

Sample A softened at 220° C; was partially molten at 250° C. whenpressure was applied; was almost completely molten at 300° C. whenpressure was applied; and rehardened (cured) to a granular solid after25 minutes at 300° C. Sample A was slightly soluble in hot m-cresol.

Sample B softened at 70° C.; was nearly completely molten at 225° C.with applied pressure; and hardened (cured) to a granular solid at 250°C. Sample B was soluble in hot m-cresol, and virtually insoluble insulfolane, DMAC and toluene.

Analysis: Calc'd. for C₆₂ H₃₄ N₄ O₁₁ :

C, 73.66; H, 3.39; N, 5.54; O, 17.41. For A Found: C, 73.21; H, 3.67; N,5.79; O, -----.

A portion of sample B was postheated in nitrogen at 300° C. for 24hours, and a TGA performed in nitrogen at 10° C./minute, showed aninflection point of 410° C.

i. Preparation of Styrene-Terminated Oligomeric Polyimide (BTAS-3).Reaction of BTCA, DAPB-3,3 and AS (8:7:2).

In the m-cresol:benzene azeotropic apparatus fitted with provisions fora nitrogen sweep, was placed a warm solution of BTCA (1.2889 g., 0.004mole) in 25 ml. of m-cresol and 10 ml. of benzene containing 1-2 mg. oft-butyl catechol. Then a solution of AS (1.1192 g., 0.01 mole) in 5 ml.of m-cresol was added and the solution was then stirred and heated atapproximately 70° C. for 15 minutes. Then a solution of DAPB-3,3 (1.023g., 0.0035 mole) in 10 ml. of m-cresol was added and the solution heatedto reflux which was maintained for 4 hours, during which time,approximately 1.5 ml. of water was collected. Then the benzene wasdistilled off. After cooling to ambient temperature, the slightly hazysolution was added dropwise to 150 ml. of methanol. The solid wasfiltered off and washed three times in 30 ml. of boiling methanol, whichcontained a trace of t-butyl catechol, for 15 minutes each time, then itwas given a final wash with inhibitor-free boiling methanol. The yellowsolid was filtered and vacuum-dried at room temperature for two days togive BTAS-3, 1.782 g. (78%) as a yellow solid. Its TGA in nitrogen at10° C./minute showed the retention of m-cresol solvent.

On a Fisher-Johns melting point block, it melted at 190°-195° C.,hardened at 205° C., resoftened and remelted at 210°-233° C., andrehardened at 268° C. Its DTA at 20° C./minute showed a meltingendotherm at 183° C. BTAS-3 was soluble in dioxane, m-cresol, DMAC andsulfolane; it swelled in tetrahydrofuran, styrene, divinylbenzene andtoluene, and was insoluble in methyl ethyl ketone.

A portion of BTAS-3 was vacuum dried at 200° C. for 36 hours andanalyzed.

Analysis: Calc'd. for C₂₇₈ H₁₄₆ N₁₆ O₅₄ : C, 72.99; H, 3.22; N, 4.90; O,18.89. Found: C, 73.55; H, 3.31; N, 5.03; O, -----.

j. This oligomer (BTAS-4) is prepared in Example 3 above. k. Preparationof Styrene-Terminated Oligomeric Polyimide (BTAS-10R). Reaction of BTCA,4,4'-Methylenedianiline (MDA-4,4) and AS (9:8:2).

In the m-cresol:benzene azeotropic apparatus equipped with a nitrogeninlet and outlet, there was placed BTCA (21.7505 g., 0.0675 mole) in 80ml. of m-cresol and 40 ml. of benzene. The temperature of the mixturewas raised to approximately 70° C. as nitrogen was passed through theapparatus, and a solution of m-aminostyrene (AS) (1.7874 g., 0.015 mole)in 40 ml. of m-cresol containing 0.1 g. of t-butyl catechol was addedover 15 minutes, and the solution was stirred for an additional 15minutes. Then a solution of 4,4'-methylenedianiline (MDA-4,4) (11.8956g., 0.060 mole) in 55 ml. of m-cresol was added and the solution wasbrought to reflux. After refluxing for 3 hours, during which 2.35 ml. ofwater was collected, a copious yellow precipitate was present. Then, thebenzene was distilled off and the reaction solution was added dropwiseto methanol. The precipitated oligomer was digested three times in hotmethanol containing approximately 0.1 g. of t-butyl catechol and thenvacuum-dried at ambient temperature for 63 hours to afford BTAS-10R,32.565 g. (98.7%), whose infrared spectrum was consistent with thatexpected for the compound.

A 2.25 g. sample of BTAS-10R was washed once with methanol to remove theinhibitor to afford 2.190 g. of inhibitor-free BTAS-10, whose DTA in airshowed a slight endotherm at 150° C., followed by an exotherm at 175° C.

Analysis: Calc'd. for C₂₇₃ H₁₄₈ N₁₀ O₄₅ : C, 74.52; H, 3.39; N, 5.73; O,16.36 Found: C, 73.38; H, 3.52; N, 5.84; O, 16.59.

l. Preparation of Styrene-Terminated Oligomeric Polyimide (BTAS-11).Reaction of BTCA, 1,3-Di(4-Aminophenoxy)-benzene (DAPB-3,4) and AS(9:8:2).

By the procedure used in the preparation of (k) above, there was reactedBTCA (1.8126 g., 0.00563 mole) in 25 ml of m-cresol and 20 ml ofbenzene, a solution of AS (0.14909) g., 0.00125 mole) in 10 ml. ofm-cresol containing 0.1 g. t-butyl catechol, and s solution of1,3-di(4-aminophenoxy)benzene (DAPB-3,4) (1.4617 g., 0.005 mole) in 20ml. of m-cresol. After refluxing for 5 hours, there was obtained 0.35ml. of water and solution had not occurred. Then the benzene wasdistilled off and the reaction mixture was slowly poured into methanolto precipitate the oligomer. The oligomer was digested thred times inhot methanol containing 0.1 g. t-butyl catechol and vacuum-dried at 40°C. to give 3.4882 g. (96.8%) of BTAS-11 as a yellow powder. A smallportion of BTAS-11 was digested again in hot methanol to remove theinhibitor for use in testing. Its infrared spectrum was consistent withthat expected for the compound.

The TGA in air showed the retention of about 3% m-cresol and aninflection point in the 500° C. region.

Analysis: Calc'd. for C₃₁₃ H₁₆₄ N₁₈ O₆₁ : C, 72.96; H, 3.21; N, 4.89; O,18.94. Found: C, 72.22; H, 3.11; N, 4.69; O, -----.

m. Preparation of Styrene-Terminated Oligomeric Polyimide (BTAS-1).Reaction of 1,4,5,8-Naphthalenetetracarboxylic Acid Dianhydride (NTCA),DAPB-3,3 and AS (9:8:2).

According to the procedure given for (1) above, there was allowed toreact 1,4,5,8-naphthalenetetracarboxylic acid dianhydride (NTCA) (2.8369g., 0.01125 mole), DAPB-3,3 (2.9233 g., 0.01 mole) and AS (0.2979 g.,0.0025 mole). There was obtained NTAS-1 as a tan powder which partiallymelted, with darkening at 220°-260° C., rehardened at 265° C., and thendid not change up to 300° C. When a sample was placed on a Fisher-Johnsapparatus at approximately 220° C., it became completely molten by 260°C. and rehardened at about 265° C.

NTAS-1 was soluble in DMAC, m-cresol, sulfolane and concentratedsulfuric acid, and swelled in hot dioxane. Its infrared spectrum wasconsistent with that expected for the compound.

Analysis: Calc'd. for C₂₈₆ H₁₄₆ N₁₈ O₅₂ : C, 73.61; H, 3.15; N, 5.40; O,17.83. Found: C, 73.74; H, 3.50; N, 5.83; O, -----.

n. Preparation of Styrene-Terminated Oligomeric Polyimide (PMAS-1).Reaction of Pyromellitic Anhydride (PMA), DAPB-3,3 and AS (9:8:2).

According to the procedure given for (1) above, there was allowed toreact pyromellitic anhydride (PMA) (2.4538 g., 0.01125 mole), DAPB-3,3(2.9233 g., 0.01 mole) and AS (0.2979 g., 0.0025 mole). Completesolution did not occur during the reaction period. There was obtainedPMAS-1, which melted at 150°-210° C., rehardened at 240° C., andresoftened at 275° C., and rehardened after 20 minutes at 300° C. PMAS-1swelled in m-cresol, and was insoluble in concentrated sulfuric acid,hot DMAC, sulfolane and dioxane. Its infrared spectrum was consistentwith that expected for the compound. Its DTA in air and its TGA in airshowed solvent retention and an inflection point in the 500° C. region.

Analysis: Calc'd. for C₂₅₀ H₁₂₈ N₁₈ O₅₂ : C, 71.22; H, 3.06; N, 5.98; O,19.74. Found: C, 71.22; H, 3.22; N, 6.17; O, -----.

B. Dipolar Cycloaddition Reactions

In Examples 11-56, three procedures, A to C inclusive, were used toprepare cycloaddition reaction products of somedipolarophilic-terminated oligomeric polyimides prepared in (a) to (n)of Part A of this Example with the two dipoles 1,4-benzenedinitrileoxide (BDNO) and 1,4-benzenedi(phenylnitrilimine) - (BDNI). However,basically, the three procedures are equivalent. Minor modifications wereintroduced to accommodate the particular systems used. For example, insome cases a highly soluble oligomer required less solvent in which toperform the reaction.

Procedure A: The acceptor was first dissolved in 18 ml. of m-cresol, bywarming if necessary. The solid dipole was added and the mixture wasstirred at ambient temperature until solution was effected. The solutionwas then placed in an air oven at 70°-80° C. for 5 to 8 days, afterwhich the temperature was raised to 200° C. for 1 day. Finally, thesamples were vacuum-dried at 200° C. for 1 day, and the weight recorded.Small samples were dried in an air oven at 200° C., 240° C. or 300° C.for 24 hours and the temperature at which they were cured designated bythe suffix, H200, H240 and H300 after the polymer number.

Procedure B: The acceptor was first dissolved in 5-10 ml. of m-cresol,by warming if necessary. Then solid dipole was added and the mixture wasstirred at ambient temperature until solution occurred, after which thesolution was then placed in an air oven at 100° C. for 24 hours, andthen at 200° C. for 48 hours. The residues were then vacuum-dried at200° C. for 24 hours and the weights recorded. Small samples were driedin an air oven at 300° C. for 24 hours and are designated as H300.

Procedure C: This procedure is a modification of Procedure B in that,after mixing, the samples were allowed to stand at ambient temperaturefor 48 hours and then were heated to 200° C. over an 8-hour period.After drying in an air oven at 200° C. for 48 hours, the residues werevacuum-dried at 200° C. for 24 hours and the weights were recorded. BDNIand BDNO were prepared as follows:

Synthesis of 1,4-Benzenedi(phenylnitrilimine) p-C₆ H₄ (C═NNC₆ H₅)₂, BDNI

1. Intermediate Terephthaloylphenylhydrazide Chloride, ##STR21##

A mixture of 5.8 g. (0.016 mole) of terephthaloylphenylhydrazide, (m.p.265° C.), 7.5 g. (0.036 mole) phosphorous pentachloride in 60 ml.anhydrous ether was heated under reflux for twenty-four hours duringwhich time the mixture remained heterogeneous. Then 20 g. phenol (0.212mole) in 20 ml. ether was added to the mixture, followed by the slowaddition of 30 ml. (0.74 mole) of methanol and allowed to cool to roomtemperature. The yellow crystals which formed were separated by thefiltration. The filtrate was concentrated at 50° C. until more crystalsappeared; these were isolated by filtration. The crude product wasrecrystallized from benzene, yielding 2.14 g. (35.0%); m.p., 216-217° C.Its infrared spectrum showed the C═N absorption at 6.3μ; the amide peak,##STR22## at 5.9μ was not present.

Analysis: Calc'd. for C₂₀ H₁₆ Cl₂ N₄ : C, 62.66; H, 4.20; N, 14.62; Cl,18.52. Found: C, 62.92; H, 4.32; N, 14.49; Cl, 18.30.

2. Synthesis of BDNI from BCNI

To 0.2 g. of BCNI in 2 ml. DMAC there was added 0.12 g. Et₃ N and themixture allowed to react with stirring at room temperature for twohours. Then 5 ml. of water was added and the resulting precipitateremoved by filtration, washed with distilled water and dried in a vacuumoven at 30° C; yield of brown powder, 0.152 g. (˜100%); m.p. 180°-185°C. (with resinification).

BDNI is used within 72 hours after its preparation.

Synthesis of 1,4-Benzenedinitrile Oxide BDNO

1. Intermediate Terephthaldehyde Dioxime, p-C₆ H₄ (CH═NOH)₂

Into a 2-liter Erlenmeyer flask were placed 45 g. (0.66 mole ofhydroxylamine · HCl dissolved in 237 ml. of water and 26.4 g. (0.66mole) of sodium hydroxide dissolved in 150 ml. of water; this mixturewas thoroughly agitated. Then 40.2 g. (0.3 mole) of terephthaldehyde,dissolved in 300 ml. of ethanol was added to the mixture, which remainedclear for a few seconds, then a large amount of white precipitateformed. The mixture was brought to reflux on a steam bath, then 200 ml.of 95% ethanol was added to dissolve the precipitate, and reflux wascontinued for 30 minutes, after which the mixture was cooled in anice-water bath, and the white crystals which precipitated were recoveredby filtration. The crude dioxime was recrystallized from a 55% ethanol45% water solution. The yield of recrystallized product was 95% based onterephthaldehyde; m.p. 220°-222° C. Its infrared spectrum showed bandsfor >C═N-- at 6.14 and 6.6μ; for --OH absorption at 3.3, 7.1 and 7.6μ;and for ##STR23## at 8.2 and 12.0μ.

2. Intermediate Terephthalhydroxamoyl Chloride, ##STR24##

Into a suspension of 2.3 g. terephthaldehyde dioxime (A above) in 45 ml.CCl₄ was passed slowly with stirring a stream of Cl₂ gas for a period of1.5 hours. The temperature of the reaction mixture was held below 0° C.by means of an ice-salt cooling bath, then the mixture was allowed toremain at room temperature overnight. The suspended solids wererecovered from CCl₄ by filtration and were recrystallized twice from 10%ethanol-90% chloroform. White crystals were obtained, m.p. 184°-186° C.

3. Synthesis of 1,4-Benzenedinitrile Oxide (BDNO)

A solution of 16.7 g. (0.0716 mole) of terephthalhydroxamoyl chloride in270 ml. of diethyl ether was added over a period of 15 minutes to a wellstirred solution of 21 g. of triethylamine (0.21 mole) in 760 ml. ofdiethyl ether; the reaction was maintained at 0°-2° C. with a salt-icecooling bath. A voluminous precipitate was formed and after stirring for10 minutes, 60 ml. of ice-water was added to the reaction mixture andstirring continued for an additional 30 minutes. Then the precipitatewas recovered by filtration, washed thoroughly 3 times with alternateportions of cold water and diethyl ether, and then dried at roomtemperature at 5 mm. Hg pressure for 18 hours. Yield 80% of theory (9.3g.) as a yellow powder which does not melt at temperature up to 300° C.The infrared spectrum showed the strong bands characteristic of thenitrile oxides at 4.3, 8.5 and 9.2μ.

Analysis: Calc'd. for C₈ H₄ O₂ N₂ : C, 60.00; H, 2.52; N, 17.50. Found:C, 59.90; H, 2.58; N, 17.37.

Table VI, below, summarized the data on the polymers so prepared.

                                      Table VI                                    __________________________________________________________________________    Data on Dipolar Cycloaddition Reactions of Various Oligomeric Polyimides                                   Molar     TGA                                    Example                                                                            Pro-                                                                              Oligomer   Dipole   Ratio                                                                              %    Cured        Break                                                                             Inflection            No.  cedure                                                                             (01) Grams                                                                              (Di)                                                                              Grams                                                                              01:Di                                                                              Yield                                                                              at ° C.                                                                      Atmosphere                                                                           ° C.                                                                       Point °        __________________________________________________________________________                                                            C.                    11   A   BTAS-1                                                                              0.505                                                                              BDNO                                                                              0.0190                                                                             1:1  100  200   nitrogen                                                                             320 (320)                           (h)                          240   nitrogen                                                                             360 (520)                 12   A   BTAS-1                                                                              0.505                                                                              BDNI                                                                              0.105                                                                              1:1  107  240   nitrogen                                                                             300 (350)                           (h)                          300   nitrogen                                                                             340 (510)                 13   B   BTAS-3                                                                              0.4478                                                                             BDNO                                                                              0.016                                                                              1:1  100  200   air    270 560                             (i)                          300   air    380 580                   14   B   BTAS-4                                                                              0.4882                                                                             BDNO                                                                              0.0640                                                                             1:4  110  200   nitrogen                                                                             380 510                             (j)                          200   air    380 490                   15   B   BTAS-4                                                                              0.4882                                                                             BDNO                                                                              0.0160                                                                             1:1  108  200   nitrogen                                                                             425 530                             (j)                          200   air    400 530                   16   B   BTAS-4                                                                              0.4882                                                                             BDNO                                                                              0.0120                                                                             4:3  104  200   nitrogen                                                                             435 530                             (j)                          200   air    375 515                   17   C   BTAS-4                                                                              0.4882                                                                             BDNO                                                                              0.0160                                                                             1:1   99.5                                                                              200   air    300 550                             (j)                          300   air    375 540                   18   B   BTAS-4                                                                              0.4882                                                                             BDNI                                                                              0.0310                                                                             1:1  102  200   air    250 550                             (j)                          300   air    400 550                   19   C   BTAS-4                                                                              0.4882                                                                             BDNI                                                                              0.0310                                                                             1:1  112  200   air    300 530                             (j)                          300   air    360 520                   20   B   BTAS-4                                                                              0.4882                                                                             BDNI                                                                              0.0232                                                                             4:3  104  200   air    300 540                             (j)                          300   air    400 540                   21   B   BTAS-10                                                                             0.440                                                                              BDNO                                                                              0.0160                                                                             1:1   92.98                                                                             200   air    390 560                             (k)                                                                 22   B   BTAS-10                                                                             0.440                                                                              BDNO                                                                              0.0120                                                                             4:3  101.26                                                                             200   air    380 550                             (k)                                                                 23   B   BTAS-10                                                                             0.440                                                                              BDNI                                                                              0.0310                                                                             1:1  101.57                                                                             200   air    390 530                             (k)                                                                 24   B   BTAS-10                                                                             0.220                                                                              BDNI                                                                              0.0116                                                                             4.3  108.18                                                                             200   air    310 550                             (k)                                                                 25   B   BTAS-11                                                                             0.2576                                                                             BDNO                                                                              0.008                                                                              1:1  104  200   air    330 555                             (l)                          300   air    390 580                   26   B   BTAS-11                                                                             0.2576                                                                             BDNO                                                                              0.006                                                                              4:3  103  200   air    330 555                             (l)                          300   air    410 585                   27   B   NTAS-1                                                                              0.4666                                                                             BDNO                                                                              0.016                                                                              1:1  110  200   air    350 510                             (m)                          300   air    350 525                   28   B   NTAS-1                                                                              0.4666                                                                             BDNO                                                                              0.012                                                                              4:3  109  200   air    350 505                             (m)                          300   air    400 525                   29   B   PMAS-1                                                                              0.4216                                                                             BDNO                                                                              0.016                                                                              1:1   98  200   air    300 515                             (n)                          300   air    380 530                   30   B   PMAS-1                                                                              0.4216                                                                             BDNO                                                                              0.016                                                                              4:3   99  200   air    310 570                             (n)                          300   air    310 570                   31   A   BTAN-2                                                                              0.5045                                                                             BDNO                                                                              0.080                                                                              1:1   98  200   nitrogren                                                                            200 430                             (a)                          300   nitrogen                                                                             300 520                   32   A   BTAN-2                                                                              0.5045                                                                             BDNO                                                                              0.320                                                                              1:4  100  200   nitrogen                                                                             200 350                             (a)                          300   nitrogen                                                                             350 550                   33   A   BTAN-2                                                                              0.5045                                                                             BDNI                                                                              0.105                                                                              1:1  107  240   nitrogen                                                                             250 400                             (a)                          300   nitrogen                                                                             330 525                   34   A   BTAN-2                                                                              0.5045                                                                             BDNI                                                                              0.620                                                                              1:4  103  240   nitrogen                                                                             250 330                             (a)                          300   nitrogen                                                                             340 530                   35   B   BTAN-3                                                                              0.2399                                                                             BDNO                                                                              0.008                                                                              1:1  103  200   air    300 520                             (b)                          300   air    370 560                   36   B   BTAN-3                                                                              0.2399                                                                             BDNO                                                                              0.0320                                                                             1:4  109  200   air    300 560                             (b)                          300   air    360 550                   37   B   BTAN-3                                                                              0.2399                                                                             BDNI                                                                              0.0155                                                                             1:1  102  200   air    320 600                             (b)                          300   air    360 575                   38   B   BTAN-3                                                                              0.2399                                                                             BDNI                                                                              0.0620                                                                             1:4  106  200   air    320 585                             (b)                          300   air    360 570                   39   B   BTAN-4                                                                              0.254                                                                              BDNO                                                                              0.008                                                                              1:1   97.06                                                                             300   air    430 560                             (c)                                                                 40   B   BTAN-4                                                                              0.254                                                                              BDNO                                                                              0.032                                                                              1:4  111.09                                                                             200   air    360 580                             (c)                                                                 41   B   BTAN-4                                                                              0.254                                                                              BDNI                                                                              0.0155                                                                             1:1  100.15                                                                             200   air    390 545                             (c)                                                                 42   B   BTAN-4                                                                              0.254                                                                              BDNI                                                                              0.062                                                                              1:4   95.41                                                                             200   air    400 550                             (c)                                                                 43   A   BTBN-1                                                                              0.5185                                                                             BDNO                                                                              0.08 1:1  100  200   nitrogen                                                                             170 530                             (e)                          300   nitrogen                                                                             350 540                   44   A   BTBN-1                                                                              0.5185                                                                             BDNO                                                                              0.320                                                                              1:4  100  200   nitrogen                                                                             200 530                             (e)                          300   nitrogen                                                                             350 560                   45   A   BTBN-1                                                                              0.5185                                                                             BDNI                                                                              0.155                                                                              1:1  107  240   nitrogen                                                                             280 550                             (e)                          300   nitrogen                                                                             340 550                   46   A   BTBN-1                                                                              0.5185                                                                             BDNI                                                                              0.620                                                                              1:4  108  240   nitrogen                                                                             250 indeter-                        (e)                          300   nitrogen                                                                             350 minate                                                                        530                   47   B   BTBN-3                                                                              0.2423                                                                             BDNO                                                                              0.008                                                                              1:1  105  200   air    280 590                             (f)                          300   air    360 610                   48   B   BTBN-3                                                                              0.2423                                                                             BDNO                                                                              0.032                                                                              1:4  110  200   air    310 570                             (f)                          300   air    350 550                   49   B   BTBN-3                                                                              0.2423                                                                             BDNI                                                                              0.0155                                                                             1:1   99  200   air    320 595                             (f)                          300   air    420 610                   50   B   BTBN-3                                                                              0.2423                                                                             BDNI                                                                              0.0620                                                                             1:4  104  200   air    320 580                             (f)                          300   air    390 595                   51   B   BTBN-4                                                                              0.255                                                                              BDNO                                                                              0.008                                                                              1:1   97.00                                                                             200   air    400 520                             (g)                                                                 52   B   BTBN-4                                                                              0.255                                                                              BDNO                                                                              0.032                                                                              1:4  101.64                                                                             200   air    340 540                             (g)                                                                 53   B   BTBN-4                                                                              0.255                                                                              BDNI                                                                              0.0155                                                                             1:1  102.33                                                                             300   air    460 620                             (g)                                                                 54   B   BTBN-4                                                                              0.255                                                                              BDNI                                                                              0.062                                                                              1:4   98.52                                                                             200   air    450 595                             (g)                                                                 55   A   BTAA-3                                                                              0.443                                                                              BDNO                                                                              0.080                                                                              1:1   96  200   nitrogen                                                                             220 350                             (d)                          300   nitrogen                                                                             340 400                   56   A   BTAA-3                                                                              0.443                                                                              BDNI                                                                              0.105                                                                              1:1  105  240   nitrogen                                                                             260 300                             (d)                          300   nitrogen                                                                             330 370                   __________________________________________________________________________     *Bracketed values are not sharply defined.                               

What is claimed is:
 1. A polymeric chain-extending and cross-linkingprocess comprising: reacting, at a temperature of about from ambienttemperatures to 300° C, a polyimide of the formula: ##STR25## whereinAr' is a tetravalent aromatic organic radical, the four carbonyl groupsbeing attached directly to separate carbon atoms and each pair ofcarbonyl groups being attached to adjacent carbon atoms in the Ar'radical,Ar is a divalent aromatic organic radical, and n is a positiveinteger of at least 1, with an anhydride of the formula: ##STR26##wherein p is 3, and Ar' is a hexavalent aromatic organic radical, thesix carbonyl groups being attached directly to separate carbon atoms andeach pair of carbonyl groups being attached to adjacent carbon atoms inthe Ar' radical.
 2. The process of claim 1 wherein Ar' in the polyimideis selected from the group consisting of ##STR27## Ar' in the anhydrideis ##STR28## and Ar is selected from the group consisting of ##STR29##multiples thereof connected to each other by R^(IV), wherein R^(IV) isalkylene of 1 to 3 carbon atoms, ##STR30##
 3. The process of claim 2wherein n is 4 to
 20. 4. The process of claim 1 wherein the reaction isconducted at a temperature above the melting point of the reactants. 5.The process of claim 1 wherein the reaction is conducted in a solventfor the reactants.
 6. The process of claim 5 wherein the solvent is aphenol of the formula: ##STR31## wherein each R¹ is hydrogen or methyl.7. A polymeric chain-extending and cross-linking process comprising:reacting, at a temperature of about from ambient temperatures to 300° C,a polyimide of the formula: ##STR32## wherein Ar' is selected from thegroup consisting of ##STR33## Ar is selected from the group consistingof ##STR34## multiples thereof connected to each other by R^(IV),wherein R^(IV) is alkylene of 1 to 3 carbon atoms, ##STR35## n is apositive integer of at least 3, with an anhydride of the formula:##STR36## wherein p is 3 and Ar' is ##STR37##
 8. The process of claim 7wherein n is 4 to
 20. 9. The process of claim 8 wherein the reaction isconducted at a temperature above the melting point of the reactants. 10.The process of claim 8 wherein the reaction is conducted in a solventfor the reactants.
 11. The process of claim 10 wherein the solvent is aphenol of the formula: ##STR38## wherein each R¹ is hydrogen or methyl.12. A cross-linked polymer prepared by the process of claim
 1. 13. Across-linked polymer prepared by the process of claim
 4. 14. Across-linked polymer prepared by the process of claim
 6. 15. Across-linked polymer prepared by the process of claim
 7. 16. Across-linked polymer prepared by the process of claim
 9. 17. Across-linked polymer prepared by the process of claim
 11. 18. Theprocess of claim 7 wherein Ar is selected from the group consisting of--C₆ H₄ CH₂ C₆ H₄ --, --C₆ H₄ SO₂ C₆ H₄ --, --C₆ H₄ OC₆ H₄ SO₂ C₆ H₄ OC₆H₄ --, --C₆ H₄ OC₆ H₄ OC₆ H₄ --, and --C₆ H₄ OC₆ H₄ --.